The Ultimate Guide: Changing Your Marine Fuel Filter

Changing the fuel filter on a boat is a relatively straightforward task that can be completed in a few hours. It is an important aspect of boat maintenance as it helps prevent engine breakdowns and other problems caused by dirty fuel. The process involves first turning off the fuel petcock and placing a receptacle to collect any spilled fuel. The old filter is then removed, and the new filter is installed, ensuring that all components are correctly sealed and seated. Depending on the type of engine, there may be a primary and secondary filter, with the primary filter being on the suction side of the lift pump and the secondary filter on the pressure side. It is also important to bleed the fuel system after changing the filters.

Prepare your tools and materials

To prepare for changing your marine fuel filter, you will need to gather the necessary tools and materials. The specific items you will require may vary depending on the type of boat you have and the fuel filter you are using, but here is a comprehensive list to guide you:

• Oil cloths or oil-absorbent pads/sheets: These are large, absorbent gauze sheets that are used to capture any spilled fuel during the filter replacement process. They are placed under the micron filter when removing and remounting it.
• Plastic zipper bags: You will need these to properly dispose of the old filter and any used rubber O-rings or gaskets.
• Fuel: It is recommended to have some extra fuel on hand. You can use a spare can of gas with a funnel to guide the fuel into the new filter. Alternatively, you can use a cooking baster to suck the fuel out of the gas can and squirt it into the micron filter.
• Sea Foam (optional): Some people choose to fill their fuel filter with Sea Foam when replacing it. This is a fuel additive that helps clean the fuel system.
• Tools for disassembly and assembly: This includes items such as screwdrivers (both thin-blade and standard), a blunt knife, a caulking gun, and a clean, lint-free rag or paper towels for wiping down surfaces and removing dirt and debris.
• New fuel filter: Make sure you have the correct size and type of fuel filter for your specific engine. Common sizes include 2-micron, 10-micron, and 30-micron filters.
• Gaskets and O-rings: You may need to replace the gasket and O-rings, so have new ones on hand.
• Fuel System Grade Thread Sealer: When installing the new filter, you will need a thread sealer that is appropriate for fuel applications.
• USCG-Approved Fuel Hose (if replacement is needed): If you are also replacing the fuel hose, ensure that it is type A1-15, which is compatible with E10 fuel and meets EPA standards for ultra-low permeation.
• Mounting materials: Depending on the installation, you may need items such as stainless steel self-tapping screws, plywood, and epoxy glue.

Before beginning the replacement process, carefully review the manufacturer's instructions for your specific fuel filter and refer to your engine manual for any additional tools or materials required.

Turn off the fuel petcock

Turning off the fuel petcock is an important first step when changing your marine fuel filter. This step is crucial to prevent fuel from draining or siphoning out of the tank. By turning off the fuel petcock, you can avoid spills and leaks during the filter replacement process.

Before turning off the fuel petcock, it is recommended to place a suitable receptacle under the primary filter to catch any residual fuel that may spill out. This is an important safety measure to prevent fuel from spreading onto other components or surfaces. Additionally, laying down oil-absorbent pads around the work area is a good practice to capture any inevitable spills or leaks.

The fuel petcock is typically located near the fuel tank. It is a valve that controls the flow of fuel. By turning it off, you can isolate the fuel system and ensure that no fuel flows out during the filter change. This makes the process much safer and cleaner.

Once the fuel petcock is turned off, you can proceed with the rest of the steps involved in changing the marine fuel filter. This may include tasks such as unscrewing the filter housing, removing the old filter element, cleaning or replacing any gaskets or O-rings, and installing the new filter.

It is important to note that the location and design of the fuel petcock may vary depending on the make and model of your marine vessel. Therefore, it is always a good idea to refer to your owner's manual or seek guidance from a marine mechanic if you are unsure about the specific steps involved in turning off the fuel petcock for your particular vessel.

Remove the old filter

To remove the old filter, begin by turning off the fuel petcock (if your boat has one) to prevent fuel from draining or siphoning out of the tank. Place a suitable receptacle under the primary filter to collect any spilled fuel. Lay down some oil-absorbent pads to capture inevitable spills.

The next step is to unscrew the T-handle on top of the filter and remove the cap. If you have a Parker Racor filter, simply lift out the old filter element and place it into a plastic bag for disposal. If you have a different type of filter, refer to the manufacturer's instructions.

After removing the top cover and T-handle, open the petcock on the bottom of the filter to remove any water and dirt from the bowl into a clear receptacle. Inspect the fuel for trash or water. Once the sediment has been drained, retighten the petcock. If the fuel is particularly dirty, you may need to disassemble and clean the bowl more thoroughly.

Remove and dispose of the rubber O-ring from the base of the threads on the T-handle. Use a thin-blade screwdriver to carefully unseat and remove the rubber gasket from the groove on the underside of the lid. The gasket can be difficult to remove, so take care not to damage the seat. With the seals removed, clean the mating surfaces and seal groove with a clean, lint-free rag.

Clean the filter housing

To clean the filter housing, you'll need to remove the old filter and clean the housing before installing a new filter. Here's a step-by-step guide:

• Place oil-absorbent pads around the filter to capture any spills.
• Turn off the fuel petcock (if your boat has one) to prevent fuel from draining out of the tank.
• Unscrew and remove the T-handle and cap from the top of the filter. The process may vary depending on the type and design of your filter. For example, if you have a Parker Racor filter, you'll need to remove the T-handle first, then the cap.
• Lift out the old filter element and place it in a plastic bag for proper disposal.
• Open the petcock on the bottom of the filter to drain any water and dirt into a clear receptacle. Inspect the drained fuel for trash or water. Retighten the petcock when done.
• If the fuel is extremely dirty, simple draining may not be sufficient. In such cases, disassemble the filter housing for a more thorough cleaning.
• Remove the rubber O-ring from the base of the T-handle threads and the rubber gasket from the underside of the lid using a thin-blade screwdriver. Take care not to damage the gasket seat.
• With the seals removed, clean the mating surfaces and seal groove with a clean, lint-free rag.

At this stage, the filter housing should be clean and ready for a new filter. Remember to follow the manufacturer's instructions and recommendations for your specific filter type and engine.

Install the new filter

Now that you have removed the old filter, it's time to install the new one.

First, drop the new filter into the housing and fill it with fresh, clean fuel. If you are using a 10-micron filter, about three-quarters full will do. If you are at sea, you can use a spare can of gas and a funnel to guide the gas into the filter. Alternatively, you can use a cooking baster to suck gas out of the gas can and squirt it into the micron filter.

Next, smear some clean fuel onto the surfaces of the new gasket and O-rings. Then, carefully reseat them into their respective grooves. Make sure the filter housing is correctly seated in the groove. Now, screw down the T-handle, complete with a new O-ring, tightening it by hand only.

If your engine has a secondary filter, it is usually mounted on the engine and close to, and immediately after, the lift pump. The engine-mounted secondary filters are on the pressure side of the lift pump, while the primary filter is on the suction side. Consult your manual for the specific details of your engine.

Frequently asked questions