How To Change Fuel Water Separator Filter

How To Change Fuel Water Separator Filter On An Outboard

On the subject of changing your boat’s fuel water separator filter, today’s guide is intended to educate you how. Even while we wouldn’t describe installing a gasoline water separator as particularly difficult, many sailors, particularly those dealing with separators for the first time, may be intimidated by the process. After discussing what fuel water separators are and why they are important, we’ll walk you through the process of installing a fuel water separator outboard motor in the following section.

What is a Fuel Water Separator?

In the automotive industry, a fuel water separator is a piece of equipment that filters water from gasoline before it reaches the engine. Filter for boats Conventional gasoline filters are not intended to catch large amounts of water; instead, fuel water separators are used to accomplish this duty. What is the operation of a fuel water separator? To put it simply, the process is as follows at its most fundamental level:

  1. Large droplets of water are separated into smaller ones by a pleated paper element. The droplets land in a water bowl located at the bottom of the gadget
  2. Here is where they stay. Those little water particles that did manage to get past the paper element are caught by a layer of silicone-treated nylon and fall back into the water bowl. In accordance with the separator design, the trapped water is subsequently expelled either manually or mechanically.

This is a broad description of how fuel water separators function – the specific water filtering method varies from separator to separator.

Do I Need a Fuel Water Separator on My Boat?

A water fuel separator filter is required in your boat, and the next question is if you require one. And, if you do, what is the reason behind it? Water, on the other hand, has a detrimental impact on your boat engine in a variety of ways:

  • Rust. Surfaces made of iron or steel that come into touch with water are more susceptible to rust. Aside from causing structural damage to your engine, rust particles may also contaminate your fuel supply. Rust particles abrasion may cause serious damage to the motor’s internal components when rust-filled gasoline passes through the engine. Abrasion. Water has a lesser viscosity than gasoline and does not provide the same level of lubrication to engine components. Water, on the other hand, is a horrible lubricant. As a result, increasing water content in your gasoline will result in increased wear within the engine. Bacterial development. In your fuel system, water can promote bacterial development and mold growth. In the event that you let these to accumulate, you will not like the process of cleaning your gasoline tank, hoses, and engine
  • Performance of the boat is poor. As a result of all of the harmful impacts of water, it is possible that your boat will begin to perform poorly. Low RPMs, sluggish acceleration, and other side effects are all possible consequences of this condition.

What you may be asking is how water can get into the gasoline, which is a valid question. In the United States, gasoline includes around 10% ethanol. In order to make the gasoline burn more efficiently, it is necessary to add ethanol to the fuel mix. Reduced pollution and maybe increased fuel efficiency on your yacht are the result of this. ethanol has the disadvantage of attracting moisture from the surrounding air, which is undesirable. This is aggravated even further if your gasoline tank is not completely filled and contains a significant amount of air.

  • What you might be asking is how water can get into the gasoline, which is a reasonable question. Fuel includes around 10% ethanol in the United States. In order to make the gasoline burn more efficiently, it is necessary to add ethanol to the fuel mix. Reduced pollution and maybe increased fuel efficiency on your yacht are the results of this. Because ethanol pulls moisture from the surrounding air, it is a bad choice for drinking. A significant amount of air is trapped inside the gasoline tank when the tank is not completely full. The following are some of the other ways that water can get into your gasoline:

One thing you might be asking is how water can get into the gasoline. Gasoline in the United States includes around 10% ethanol. In order to make the gasoline burn more efficiently, ethanol is added to the mixture. This cuts pollution and may also make your boat more fuel-efficient in the process. It is ethanol’s drawback that it pulls moisture from the surrounding air. This is made more worse if your gasoline tank is not completely filled and contains a significant amount of air. Aside from this, water may enter your fuel system in a variety of ways, including:

How to Install a Fuel Water Separator on an Outboard

Let’s take a look at the installation of the gasoline water separator outboard.

Necessary Tools and Supplies

If you want to install an outboard fuel water separator, you will need the following equipment and materials.

  • Drill the mounting holes with drill bits that are the proper size for the mounting holes. The following tools are required: spanner (for installation of hose connections and blanks)
  • Screwdriver. Fire extinguisher for the protection of the boat
  • A container for storing gasoline
  • Rags for cleaning up after the installation

You may also require the following items:

  • To isolate the separator, a ball valve or blanking plugs are used. The gasoline hoses are connected to each end of the fuel water separator. The gasoline hoses are held together using jubilee clips/clamps.

Step 1. Cut Off Electricity and Fuel Lines on Your Boat

Before beginning any installation on your yacht, you should turn off the electrical and fuel lines. This is done in order to prevent electrocution and gasoline leaks when disconnecting your fuel lines in order to install the separator.

At this point, you should also determine which gasoline lines will require blanking and which will not. Please keep in mind that if you are installing the separator indoors, you should also open all of the hatches to allow for enough air circulation.

Step 2. Prepare the Fuel Water Separator for Installation

After that, unpack your separator and double-check that you have all of the essential components. After you’ve double-checked that everything is in place, you can begin assembling your fuel water separator. Because the assembling procedure varies from separator to separator, you should refer to the instructions that came with your device for more detailed instructions. It is also possible that you will wish to pre-fill your separator with gasoline, though this is not required. This method allows you to displace the air within your vehicle and prevents significant volumes of air from entering your fuel system when filling.

Step 3. Locate a Suitable Spot for the Separator

Place your gasoline water separator in a prominent and easily accessible area on your fuel tank. This allows you to quickly check for water in the separator, empty it, and change the filter if required without having to dig around. It’s also a good idea to have your priming bulb immediately accessible. Additionally, the separator’s placement should be free of any moving hoses or cables that might cause the separator to rub against the surrounding objects.

Step 4. Mark Installation Points and Drill Mounting Holes

Mark the locations where the divider will be installed. Placing the separator against the site and marking the mounting holes with a pencil can help you identify the mounting holes. Additionally, you should validate that you have selected an appropriate location for your fuel water separator at this time. In order to be effective, the separator must be oriented vertically, and its intake and output gasoline lines must be placed in a suitable location for you without kinking. It should also be installed in the gasoline line that leads to the engine, but before any filters, primers, fuel pumps, or regulators are installed.

Engine for a Motor Boat

Step 5. Install the Separator Along with Valves and Hoses

After that, install the fuel water separator.

  1. If you’re going to use a ball valve for safety reasons, make sure you place it on the intake side. When it is time to replace the fuel filter, you will be able to quickly and conveniently stop the flow of fuel. Fuel sealant should be applied to the threaded part of the ball valve before installation. Then, using a spanner, attach the ball valve to the separator. After that, attach the hose connections to the separator, once again sealing the threads with gasoline sealant and tightening the connectors with a spanner. If there are any ports that need to be blanked, either blanking plugs or extra ball valves should be used. Jubilee clamps or clips should be used on each of your hoses
  2. Two clamps per hose
  3. Make certain that your hose arrangement corresponds to the arrow direction of the separator. Connect your hoses to the hose connections that you placed in step 3 of this procedure. All of the jubilee clamps and clips should be tightened.

Step 6. Bleed the Fuel Water Separator

Fill your gasoline system all the way up to the engine. Afterwards, connect the gasoline hose to the engine. Squeeze the priming bulb on an outboard motor until it becomes firm.

Step 7. Perform Last Checks and Start the Engine

Ensure that there are no visible leaks or gasoline residue anywhere on your boat before turning on the engine and starting it. Check the settings one more time to make sure everything is in working order. Finally, turn on the engine and make sure the water cooling system is working properly. Check for leaks in the fuel water separator setup that you have installed. In the event that everything is in order, you should next take a trip on your boat. Accelerate to full power and check to see that you are getting enough gasoline to the engine and that there are no leaks in any of the lines.

Choosing the Right Fuel Water Separator for Your Outboard

We recommend that you conduct further study about gasoline water separators in order to make the best decision.

We’ll still go over some fundamentals farther down the page. You should be able to find a fuel water separator at your local marine supply store or through internet vendors like Amazon and eBay. Here are a few websites where you may make purchases:

  • Store for Marine-Related Products Even though Marine Products supplies a somewhat small selection of fuel water separators, it is still worth your time to look them over. Marine Wholesalers & Distributors, Inc. Wholesale Marine has a significantly larger and more extensive selection of fuel water separators, including freestanding separators as well as kit separators. Amazon If none of the two preceding businesses had anything suited for your requirements, then you should check out Amazon. In addition to free delivery on many of its items and simple return policies, Amazon also provides countless buyers’ testimonials to peruse, as well as other useful advantages to Amazon Prime members.


Your fuel water separator’s filtration system should be capable of collecting particles as small as 10 microns in order to properly filter out water.

Fuel Water Separator Form-Factors

Separators for marine fuel water are offered in two different configurations: solo separators and kits. The separator and mounting hardware are included in the kits. Avoid purchasing a gasoline water separator kit unless you are certain that you have all of the essential components.

Single and Dual Marine Fuel Water Separators

You should keep in mind, for example, that certain fuel water separators are designed for systems that have two tanks or two engines. You may use similar separators on single-tank/engine boats as well, but you will need to seal off one of the separator’s portions in order to do so successfully. Kits for single-tank/engine installations often contain all of the necessary fittings and blanking plugs, but you should always double-check this before purchasing anything.

Bowl Material

Plastic bowls are commonly seen in fuel water separators designed for outboard motors. Ensure that the inboard fuel water separator you purchase has a glass bowl if you intend to use it on a boat. In the case of a fire, glass bowls will not be harmed or damaged. You may also use a metal bowl, but they are not transparent and hence do not allow you to clearly check the bowl inside and outside the bowl.

Frequently Asked Questions

The fuel water separator should be installed in the outlet line that provides gasoline to the engine, but before any priming bulbs, additional filters, regulators, or fuel pumps are installed.

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How Often Should You Change a Fuel Water Separator?

Although it is not necessary to replace the whole fuel water separator, it is recommended that the filters be updated on a regular basis. To maintain appropriate engine performance, 1-2 times per year should be adequate.

Do You Have to Fill the Water Separator with Fuel Prior to Installation?

Pre-filling gasoline water separators with fuel is a smart practice since it prevents huge volumes of air from entering your fuel system, which is bad for performance. Petrol is displacing the air in your separator before to installation, therefore filling it with fuel before installation is a good idea.

How to Change Fuel Water Separator Filter – Conclusions

You should now be able to change the fuel water separator filters on a yacht with ease! Not only that, but you need also be aware of the proper way to select a gasoline water separator for boats! How about reading a few more posts on our boating blog once you’ve finished reading this article?

Installing a Fuel Water Separator

Bad gasoline is the death knell for a boat because it clogs the system, causes the engine to shut down, and leaves you stranded without a way to go back to shore. Even so-called clean gasoline, due to the presence of ethanol in it, might cause problems with a fuel system. What is the solution? Making use of a water-separating fuel filter to pass the gasoline through A remote filter is pre-installed in the gasoline system of many new outboard and inboard boats, while many older boats do not have one.

Many older vessels, on the other hand, do not. No need to be concerned: you may purchase a kit from West Marine or another supply store and complete the installation over the weekend. Overall, it will take less than 3 hours to finish the installation process.

Tools and Supplies to Install Marine Fuel Water Separator

  • When it comes to boating, bad gasoline is the death knell since it clogs the system, chokes the engine, and leaves you stranded without a means of getting back on the water! It is possible that even so-called “clean” fuel, due to its high ethanol level, could produce problems with a fuel system. Which brings us to the answer. Making use of a water-separating fuel filter when running the fuel A remote filter is pre-installed in the fuel system of many new outboard and inboard boats, and this is an excellent feature. Many older boats, on the other hand, do not have this capability. No need to be concerned: you may get a kit from West Marine or another supply store and complete the installation over the weekend. The installation will take less than 3 hours to finish in total.

How to Change a Fuel Water Separator

Step 1: To begin, you’ll need the appropriate equipment. An outboard fuel water separator is typically comprised of a filter with a transparent plastic collection bowl, which is common in the industry. If you’re using an inboard engine, utilize a filter with an aluminum bowl for gas and a transparent glass or plastic inspection bowl for diesel for better performance. It is also possible to utilize a disposable filter without a collection basin. Step 2: Open the hatches to allow for enough airflow.

  • Alternatively, you may plug the line by inserting a bolt and tightening it with a hose clamp.
  • The hoses should be able to reach the engine and the tank without kinking or making severe twists as they go through the system.
  • To attach a painted piece of plywood to the hull side as a mounting plate, epoxy-glue it in place with contact cement.
  • When installing the gasoline filter’s fittings, make sure you use thread sealant on the threads.
  • Then, using thread sealant, screw in the gasoline fittings for the filter, and put some motor oil on the gaskets or O-rings for the element and inspection bowl.
  • Boating Magazine is a publication dedicated to boating.
  • Double-clamp hard, but avoid pinching the rubber hoses in the process.
  • Step 6: Start the vehicle’s engine.
  • This schematic depicts a finished fuel filter installation, with alternative designs for outboard and inboard engines included for reference.
  • Boating Magazine is a publication dedicated to boating.

What Size Fuel Water Separator Do I Need?

The majority of manufacturers recommend a 10-micron “spin-on” filter for the optimum performance when dealing with E10 gasoline. Working with your engine manufacturer will assist you in matching the right filter to the gasoline system, or you may purchase a filter kit from respected manufacturers like as Racor, Sierra, Moeller, Mallory, or Tempo to do the matching for you if you prefer. These kits typically comprise the filter element, a collecting bowl (usually made of transparent plastic for outboards and aluminum for inboards), and a mounting bracket or head unit made of aluminum or stainless steel, among other components.

Some kits may contain the threaded fittings for the hose barb, which might be made of brass or stainless steel.

How to Change Your Mercruiser Water Separating Fuel Filter

  1. 1. Turn off your battery switches or separate the batteries from the boat. 2. Turn off your gasoline supply valve (if equipped). Advertisement
  2. 3Assign a fan to the bilge and work area to provide ventilation. 4Put some absorbent towels beneath the filter to capture any gasoline that may have escaped
  3. 5Remove the old fuel filter with the help of a fuel filter wrench. 6 Empty the old gasoline from the filter into a clean white bucket and inspect the old fuel for signs of particles or water.
  • A big amount of dirt or water in your previous fuel filter should prompt you to plan another fuel filter replacement for after your next boating excursion.
  1. Seventh, check to see that the old filter O-Ring has been completely removed from the filter mount bracket. Cleaning the filter bracket with a clean cloth and inspecting the areas where the o-ring will be required to seal
  2. 9Replace any filter brackets that are broken. 10Examine your new filter in its entirety. 11Pour some clean gasoline into the filter to make starting the engine simpler
  3. 12Consider the new filter o-ring and make certain that it is correctly positioned on the filter. 13Apply a little amount of clean engine oil on the new o-ring
  4. 14Tighten the new filter onto the filter bracket by hand until it is secure. 15Use the filter wrench to tighten the filter down another half turn or to the degree recommended by the filter manufacturer. Never overtighten a filter’s threads. 16Clean up any spilled gasoline and exhaust emissions from the surrounding area. 18Start your engine by opening your fuel valve. 18Start the boat’s batteries by connecting them or turning them on. 19Run the boat through a test run and look for gasoline leaks as soon as possible. Advertisement

Create a new question

  • Question What is the location of the fuel filter on a Mercury Mercruiser 3.0 liter? The gasoline filter may be found beneath the fuel pump on the right side of the engine. It is equipped with a stainless lock wire that prevents the pressure screw from becoming loose. The filter bowl will be able to be removed when the wire has been severed and the pressure screw has been freed with a 10 millimeter wrench. QuestionHow do I ensure that gasoline is going to the motor after changing the filter on my boat’s fuel system? After inserting the replacement filter, switch the ignition key to the “on” position (not the “start” position) for a few seconds to ensure that the fuel injectors are working properly. Keep an ear out for the low whine of the electronic fuel pump as it begins to gain pressure. When you hear the pump come to a halt, turn the key off. Restart the engine by turning the key again. If the gasoline pump begins for a very little period of time, it implies that the filter has been filled and the system has been pressured. If the fuel pump continues to operate for more than a second, repeat the off-on cycle many times more. For carbureted boat engines, if your engine is not fuel injected, you should visit a local marine mechanic since priming fuel systems on these engines is beyond the scope of internet DIY guidance.

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  • Replace your filters on a regular basis
  • Have replacement filters and a filter wrench on hand
  • And Make a note on the gasoline filter using a marker to indicate when it should be replaced. Keep a journal and keep all of your receipts
  • Some engines have more than one filter, so see your Owner’s Manual for further information.


  • Avoid using sparks or open flames
  • Stay away from moving elements such as pulleys and belts
  • Work outside where there is ample ventilation
  • And wear protective eyewear. Avoid coming into contact with gasoline since it might cause harm to the skin.


Things You’ll Need

  • Cleaning the bucket with an absorbent cloth or rag is recommended. A new fuel filter and Fuel Filter Wrench are also recommended.

About This Article

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Did this article help you?

I’m going to swap over to 2 micron racor filters as soon as I take out all of the other on-engine filters during my next service appointment, which will be shortly (parts currently on order). Some might argue that I’m making a mistake since a 2 micron filter will clog much more quickly than a 10 micron filter. A digital vacuum gauge will be positioned remotely at the console, with the transmitting device put on a T fitting on the engine side of the racor base, according to my design plans. I have an HPDI, and after consulting with a reputable dealer, they advised that the threshold at which any filter on my engine should be replaced is 4″ of mercury vacuum pressure (200 HPDI).

I do intend to have a spare filter and wrench on board in case something goes wrong.

Anyone anyone interested in doing this?

Why You Should Pre Fill A Fuel Filter or Water Separator!

You might spend hours and hours reading discussion boards or watching YouTube videos of individuals disputing whether or not it is necessary to pre-fill gasoline filters and oil filters before driving. It appears to me that the oil filter dispute is often fought between diesel enthusiasts. That is not something I will be covering here, so if you are looking for diesel oil filters, this will not be of use to you. What this article is about is whether or not you should pre-fill a boat’s fuel filter or water separator.

You will not injure the engine in any way, and it will make the job of the engine’s fuel lift pumps much simpler.

Here is a summary of the most often cited advantages and disadvantages in this discussion.

How The Fuel System Operates

Understanding even a basic understanding of the gasoline system can assist you in determining whether or not it is a good idea to pre-fill the fuel filters. This is not intended to be a thorough or exhaustive overview of the subject matter. Simply said, this will aid in the comprehension of what is being place. As a result, all engines, whether inboard or outboard, gasoline or diesel, are equipped with fuel pumps that draw fuel from the fuel tank. Each manufacturer has their own requirements for how much vacuum each pump can produce and how much power it can draw.

Now comes the heated argument over pre-filling.

It is important to note that while replacing the gasoline filters on your boat (including anything with a fuel water separator), if you place a dry filter on the bracket, you have just introduced a significant quantity of air into the closed fuel system.

In addition, the distance between the tank and the pump must be taken into mind.

Air trapped in the gasoline filter over a short distance is not as taxing on the pump as air trapped over a longer distance. Regardless of the distance, though, the gasoline pump is still having to work extra hard to keep up.

Why We Pre Fill Fuel Filters

Pre-filling all of my gasoline water separators is the primary reason for this practice. Having an air pocket in the fuel system is no longer a concern as a result of this. With a fully charged water separator, the problem of having so much air in it is no longer an issue. We are now talking about a modest amount of air that will make its way through the system, without causing the gasoline pumps to become clogged with air. Air locking the gasoline pumps may quickly escalate into a major headache.

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Keep in mind that we’re talking about water separators and boat gasoline filters right now.

That will be the subject of our next discussion.

This is why pre-filling the gasoline filters is such a wonderful practice to get into.

What To Do if the Engine Won’t Start After Changing the Fuel Filter?

In certain cases, the engine is unable to remove all of the air from the system, and you are forced to fiddle with the priming bulb, which is located on the engine side of the water separator. It is necessary to remove air from the fuel system after changing the fuel filters if the fuel filters were not previously pre-filled with gasoline. This signifies that you are manually removing air from the fuel system, which is not recommended. The procedure for doing so is rather straightforward, although it can be a major pain depending on where the priming bulbs are located in the boat.

  • It is important to check that the priming bulb is located on the engine side of the water separator bracket. Remove the gasoline pipe that connects the priming bulb to the engine and disconnect it from the engine. The arrow on the primer bulb should be towards the sky, and the primer bulb should be held vertically up or down. (It is critical that you DO NOT hold the priming bulb horizontally
  • This is critical.) Before you let go of the priming bulb, place your finger over the barb where you had previously withdrawn the gasoline hose. After that, let go of the bulb. Remove your finger from the priming bulb when it has expanded and immediately squeeze the primer bulb. Then, while holding the bulb in your hand, swiftly place your finger back on the barb and release the bulb. Continue to perform this activity until you have manually primed the gasoline system and have fuel in the primer bulb
  • If necessary, repeat the procedure. Afterwards, squeeze the bulb until just a little quantity of fuel is released, and then immediately reconnect the fuel pipe to the bulb. Continue to pump the priming bulb until the engine is completely filled with gasoline and you are able to start the engine up. Please remember to re-tighten the hose clamp afterward.

For further information on how to prime a gasoline system or how to locate an air leak, please see the links below. Check read this article we published on the steps you need to do to have it fixed!

What About Engine Fuel Filters?

Engine fuel filters, on the other hand, are a different issue. This is a little quantity of air, in my perspective, and we are talking about it. Personally, I do not pre-fill the gasoline filters in my automobile’s engine. This is true unless the filter is a canister or a water separator kind. To begin, it is vital to understand that I mostly work with outboard engines. As a result, the gasoline filters that they have are mostly inline fuel filters with fast disconnect connections, rather than bulk fuel filters.

I’m sure you could pre-fill this if you wanted to, but I don’t believe it would be of much use to you in terms of efficiency.

I believe this is due to the fact that I do not pre-fill any of the engine fuel filters.

What About Engine Oil Filters?

The same might be stated for the oil filters on your vehicle. According to the gasoline outboard engine business, most oil filters are installed on the engines upside down or at an angle to the engine’s bottom. Because of this, pre-filling them is nearly difficult. Unless, of course, you prefer creating a giant oil puddle. The pre-filling of oil filters is another thing that I don’t understand when it comes to gasoline outboard engines. I don’t see why it is essential in this case. Diesel, on the other hand, may be different.

Because of my little diesel expertise, I’ll refrain from participating in that discussion!

The way most outboards work is that the crankshaft spins, which powers the oil pump, which drives the engine.

Nothing like immediately shooting 80 PSI of oil into the filter, shredding its element; this is quickly remedied as the engine begins to run and the oil system is back up and functioning correctly without causing any harm to the filter element.

The Pros to Pre Filling

Once again, we’re talking about gasoline and diesel fuel water separators. There are several advantages to pre-filling. The most important ones have already been mentioned. Because it removes the need to fill all of the fuel systems with air, it is more environmentally friendly. Keeping the fuel injectors clean and reducing the priming load on the engines’ lift pumps are two ways to save money. Along with saving yourself the time and irritation of removing the priming bulb and physically purging out all of the air from the fuel system, you’ll also be saving yourself some money.

The Cons to Pre Filling

As for the disadvantages, they are as follows: There’s really just one reason that comes to mind. This is done in order to check for air leaks in the fuel system. Theoretically, if there are no leaks in the fuel lines and the filters are not wet, the engine should run OK. The fuel pump should be capable of sucking fuel from the tank while also purging away any remaining air. Once again, we’re talking about a lot of stress and a lot of labor being placed on the gasoline pumps’ shoulders. However, theoretically speaking, it should be able to accomplish this without encountering any difficulties.

Which, to be quite honest with you, means that if there are any air leaks in the fuel system, you will be made aware of them.

We’re talking about problems with the engine running, running out of gasoline, and WOT issues. Incorporating air into the fuel system and atomizing the fuel prior to the engine performing this function with the injectors might cause all sorts of random problems.

Tell Us What You Think

So, what is your point of view? Do you believe that it is preferable to pre-fill or not to pre-fill is more important? What are your thoughts, diesel-heads, on the subject? What is your point of view? What is the greatest option for Diesel? Please share your thoughts in the comments box below! We also have an article on What Ethanol Fuel Does To Your Engine and How To Burn It Safely that you might be interested in reading as well. You might also be interested in learning why a boat’s fuel tank overflows as it is being filled, as well as the procedures to take to prevent this from happening again.

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You can also make a donation by clicking on the give button here or on the right-hand side of the page! It is quite beneficial to us, and we are extremely grateful for your assistance! Thank you for taking the time to read this, and we look forward to hearing your thoughts and opinions. Then we hope you would visit our YouTube channel, Born Again Boating, and learn more about what we do. We provide a wide range of how-to videos, DIY boating projects, and outboard servicing hints, tips, and tricks for you to enjoy!

Changing fuel filter/water separator?

Author Comment
Mark77Registered:Posts: 169
Posted Reply with quote1

I changed my water separator/fuel filter today(oil filter type, no bowl). I think it’s tight and good. I was just wondering, where does the air that is in the empty filter go? I ran the engine for some minutes at idle, no problem.I am now thinking maybe I should have filled the filter with fuel before screwing it on there. No mentioning of this in the instructions though, it just tells you to lube the O ring and screw it on, and start the engine to check for leaks.
torewGold Level Member 3-2010Registered:Posts: 2,145
Posted Reply with quote2

The fuel pump has a built in vapor separator that handles the air. As far as I have understood it.
SteveWrightSilver Level Member 3-2010Registered:Posts: 148
Posted Reply with quote3

What I have done (necessary or not?,but no problems).after installing filter (mine has sight bowl);prime bulb, turn key to activate pump (8 seconds +-) turn off, prime bulb, turn key on again (never trying to turn key fully to start) allowing pump to run the 8 seconds,etc. As Torew suggests;fuel pumpvapor separator handles the “trapped air”.
torewGold Level Member 3-2010Registered:Posts: 2,145
Posted Reply with quote4

I exchanged the bowl with a see-through type, and at the same time replaced the motor filter with the water separating “oil-filter” type. Pumped the primer, and started the motor. No problems at all. Had to do oil priming three times, because I had re-routed the oil hose, but did not need to do anything more with the fuel supply.
Posted Reply with quote5

Ok thanks guys.I tried the hand bulb many times after I changed the filter, but I didn’t feel I could pump anything, engine on or off. But it ran fine so not really a problem, so far. Lets see what happens when I take it for a run.
Posted Reply with quote6

I took it for a run yesterday and didn’t notice anything odd at all. Seems to be ok to change the fuel filter without priming or filling it up before screwing it on there.
SteveWrightSilver Level Member 3-2010Registered:Posts: 148
Posted Reply with quote7

The instructions sent w/ “kit” (head,filtersight bowl); as well as instructions on side of replacement filtero-rings,stateto fill with fuel before screwing to head. in your case the pressurized system along w/ vapor separator was all you needed?
Posted Reply with quote8

On the filter I use there was no mentioning of filling it up, but others might be different. I have run it for over an hour after changing it, and no problems.
Posted Reply with quote9

I just changed mine about a week ago.I DIDN”T fill it with fuel.I just started it like I always do.Turn the key ON, Wait for the idiot lights to cycle ON the OFF then hit the starter.The engine started up just like it always does.
torewGold Level Member 3-2010Registered:Posts: 2,145
Posted Reply with quote10

I started mr 40 today, after almost a year. Took it off a boat this winter, put it on a new now, had the fuel hose off and a new filter inside the boat. Pumped until the bulb was firm, an cranked it. Started on the first beat, and did not miss a beat after that.
SteveWrightSilver Level Member 3-2010Registered:Posts: 148
Posted Reply with quote11

Instructions on the racor filter.Attached Images
Posted Reply with quote12

Could it be because there are 2 parts on that filter and not only one like the one I have?
SteveWrightSilver Level Member 3-2010Registered:Posts: 148
Posted Reply with quote13

Obviously it is not critical.; but your original thought was correct;” should have filled with fuel before.”I have filledmy oil filters (automobile)full of oil before screwing them on for years. Those that are horizontal, I fill orsaturate w/ oil to the point it doesn’t flow out while screwing on. It just a simple thing to domakes sense to me?

Fuel / Water Separator Testimonials

Perfect Filtration works tirelessly to discover the best solution for each and every one of our customers. We specialize in resolving your fuel filtration problems while also saving you money. Check out the testimonials from some of our happy clients in the section below.

Tired of water, downtime, and changing the OEM fuel filters so often:

We are a huge service firm that provides services to the power and phosphate industries. We have highly costly vacuum trucks, stainless steel hydraulic pumps, and (high pressure) pressure washers on our fleet. We cannot afford downtime for things that may be avoided, and we are extremely concerned about the condition of our equipment and the effectiveness of our preventative maintenance program. If we install PFS’s 285V “Ultimate” Fuel / Water Separators on our equipment, they will remove 99.9% of the water as well as particles as tiny as 1 micron in size, including dirt, bacteria, algae, silt and soot.

Our OEM fuel filters should last up to a year without needing to be replaced if we use their on-board main fuel filter, and we should only need to replace their filter element every 1,800 to 2,000 hours or every 80,000 to 100,000 miles if we use their on-board primary fuel filter.

Because of the rain and temperature variations, we were receiving water in the fuel tanks.

Our OEM gasoline filters are capable of lasting a year without needing to be replaced.

This product provided a speedy return on our investment, and we now have peace of mind knowing that our pricey equipment is safe at all times. We also placed PFS systems on our engine oils and bulk storage fuel tanks, as well as on our diesel generators.

Tired of fuel injector repairs and replacing OEM fuel filters so often:

We are a huge construction firm based in Florida with hundreds of pieces of heavy equipment at our disposal. We were searching for strategies to lower the cost of fuel injector system repairs as well as the frequency of service calls resulting from contaminated gasoline. RESULTS: Since putting certain fuel systems on our bulk storage gasoline tanks, we have seen a reduction in the number of service calls related to unclean fuel, as well as an increase in the life of the OEM filters. Off–road diesel, on–road diesel, gasoline, and jet fuel tanks are among the ten systems on our truck.

Additional systems are available for bulk storage engine oils, bulk storage hydraulic oils, and air pre-cleaners.

Greatly reduced costly downtime:

It is critical to the profitability of our huge construction firm, which employs hundreds of pieces of equipment, that the machines be operational at all times. On the newer Tier 2 and Tier 3 engines, we began to see power reduction and filter clogging before the manufacturer’s warranty had expired. We made the decision to install a PFS Ultimate Fuel / Water Separator to see if it would alleviate the situation. AS A RESULTS, we have fully eliminated our power loss, downtime, and early filter clogging issues.

“We feel that this gasoline filter should be included as standard equipment on all Tier 3 and Tier 4 engines.”

Komatsu Dealer:

We are a heavy equipment dealer that is constantly on the lookout for goods that can lower our clients’ maintenance expenses while also reducing machine downtime. Our previous clients who were utilizing PFS Ultimate systems convinced us that we should become a distributor and promote their high-quality filtering products as well. When it comes to modern equipment, we recognize the need of using ultra-clean gasoline and lubricating fluids. To be more specific, the newer Tier 2 and Tier 3 engines demand ultra clean fuel, and the Ultimate Gasoline / Water Separator has solved this problem for many of our clients, both with bulk storage fuel and on the engines themselves.

PFS filters contaminated fuel for the U.S. Military:

The United States Military has a contaminated fuel tanker load of JP4 fuel for the Tomahawk cruise missiles on the way to the Pentagon. PFS was called in to filter the tanker since the contamination levels were 3.25 milligrams per liter when they arrived. Using the Ultimate depth-type fuel filter system, the contamination level was reduced to less than 1 milligram per liter of solid particles after the fuel was filtered through it. They determined that the new filtered fuel met or surpassed their requirements, and the fuel was released and utilized to fuel the cruise missiles.

Contractor with the government

Bio-diesel filtration for the U.S. Air Force:

When the United States Air Force encountered some bio-diesel fuel that was heavily contaminated with water and solids, they sought to have the contaminates removed using a filter system. In their C-300 refueling truck, they installed an Ultimate Model 6275 Gasoline/Water Separator that allowed them to filter the contaminated fuel via the filtering system. Fuel analysis samples were collected and forwarded to the Military lab for examination. The initial set of results were so spectacular that the technical staff could not believe their eyes.

The biodiesel fuel had virtually all of the water removed from it, and the particle levels were several times lower than those of fresh new diesel fuel.

More systems for their fuelling vehicles and bulk storage filling stations have been acquired by the military since then, and the final goods are now being recommended by the military to other base sites. Scott Air Force Base is a military installation in the United States of America.

Ultimate systems installed on multi-million dollar blue water yachts:

The Cape Horn Trawler Corporation was seeking for a high-quality fuel filtration system that would filter the fuel as it entered the vessel as well as filter the fuel as it was transferred from tank to tank on the ship. For this OEM yacht builder, PFS created a stainless steel system with 1 micron filters to suit his specifications for the system. A total of four of the Ultimate Fuel / Water Separators are installed on each of the super yachts that Cape Horn manufactures. These boats are capable of traveling long distances in rough weather.


No more water, bacteria, and algae problems:

The reliability of our machines is critical because we are a huge corporation with hundreds of pieces of equipment. We have been using PFS products for some years and have chosen to equip all of our fuel service vehicles with Ultimate Fuel / Water Separators in order to assure that every time we fuel up a piece of equipment, the fuel is super clean and free of water. Increasing engine uptime will pay for itself through fewer service visits and longer OEM filter life, as well as higher engine performance and longer engine life.

Value added product for OEM’s:

We are a significant original equipment manufacturer (OEM) dealer for power generating and heavy equipment. As a result, we were seeking for a gasoline filtration device that we could give to our consumers in order to guarantee that their fuel was free of contaminants when they were most vulnerable. PFS provided us with a unit to evaluate, and the findings were outstanding. Our expectations for the cleanliness of the gasoline were fulfilled and exceeded. For bulk storage fuel filtering, we use the Ultimate portables; for existing power generating tanks and engines, we utilize the Ultimate stationary systems; for brand new power generation at the plant, we select the Ultimate Fuel / Water Separators.

It is because of the fuel purity and extended filter life that we choose the systems.


Need to Prime Replacement Fuel/Water Separator?

You are currently using an out-of-date web browser. It is possible that this or other websites will not show correctly. You need either upgrade your browser or switch to another one. I will be changing the 10 micron fuel/water separator aboard the boat as part of the preparations for the next season (Yamaha blue canister). Is it necessary to fill the new one with gas before putting it in operation? My online investigation on this has shown conflicting results – some advise to do it, while others claim that the usual course of starting and running the engine will fill it up and everything will work out perfectly.

  1. I’m curious if anyone has any first-hand knowledge of this.
  2. There are 412 messages with a reaction score of 198 and the location is Wisconsin.
  3. That is something I have never done before, so I’m not sure if it is something I should do in the future.
  4. I don’t like spilling or smelling gas.
  5. LocationColoradoMessages1,159Reaction score742Location What is the frequency with which this has to be changed?
  6. I’m planning on doing my once a year.
  7. Text messages89Analysis of reactions15 I have not replaced mine yet, but the service representative at the dealership where I purchased my boat expressly instructed me to make certain that gas was injected into the new fuel/water separator before installing the new one.

The bottom line is that when I change my oil, I will be putting gas in it.

Also, make certain that the seal on the new filter is lubricated.

Yamaha recommends changing the oil every 50 hours.

Also, make certain that the seal on the new filter is lubricated.

What I don’t get is why you would need to fill it with gas before you could put it in place.

When you turn the key (but before you turn the key further to actually start the engine), the electronic fuel injection (EFI) should fill that reservoir with fuel.

A cranking motion must be initiated, or the motor must be going.

A moderator made the following edits: Thank you for your contributions.

After emptying the current filter contents into a bucket or jar, their main outboard mechanic suggested I put the old filter back on (he didn’t say what to do about filling it), run the boat to see if there was any water in the gas from sitting there all winter, then remove the old filter for good and replace it with a new one.

  1. There are 412 messages with a reaction score of 198 and the location is Wisconsin.
  2. I just let everything rest and separate out to see what was there before moving on.
  3. After that, refuel the separator with gas and turn it back on.
  4. As a result, your circumstance may be different from others’.
  5. When things become tough, I think about doing it on a regular basis.
  6. Reaction score68Messages213Reaction score68 Let’s get right to it.
  7. It should be changed once a year.
  8. I strongly advise you to do the same.
  9. At the conclusion of the season I pinch off the gasoline line between the filter and the motor in order to drain the entire tank of petrol.

Fuel may change to varnish in a matter of months, therefore this prevents any fuel in the engine from turning to varnish and blocking up a small orifice. Excellent work with the priming bulb. That’s how I go about it. This is only my two cents’ worth of input. A moderator made the following edits:

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Your diesel filter water separator explained

What if I told you that moisture from your diesel engine can sneak into your fuel system and contaminate your diesel fuel supply? This is less of a concern for gasoline-powered automobiles since diesel engines (unlike gasoline-powered automobiles) do not have vapor pressure to displace air. With another way of putting it, as the gasoline tank heats up, the air expands and is driven out of the tank. Due to the fact that, when the tank cools, humid air is pushed back into the tank and water condenses on the colder tank walls, the situation is not ideal.

In addition to human mistake, infiltration while refueling, and water leaks into the tank are all potential sources of contamination for your gasoline.

What are the dangers of having water in your fuel?

The presence of water in your gasoline can result in a range of various difficulties, including:

  • Rust is caused by water coming into contact with iron and steel surfaces. It is possible that small particles of rust that get into the gasoline can cause abrasive wear to components, which will eventually lead to part failure. Metal corrosion can occur when water is coupled with acids in the fuel. This is true for both ferrous and non-ferrous metals. When abrasion exposes newly formed metal surfaces that are prone to corrosion, the consequences are significantly more severe. Abrasion: Because water has a lesser viscosity than diesel, it does a poorer job of lubricating moving components than diesel does. As a result, there is increased wear. In this case, the pitting is caused by the flashing of water on hot metal surfaces of components. The development of microorganisms in water can result in slimes that contaminate your fuel and acids that destroy your tank and fuel system. The engine is unable to start because the diesel has been polluted by water, which damages the injection system and prevents it from starting.

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