Outboard Fuel Maintenance: Replacing The Water Separator

Replacing the fuel water separator on an outboard motor is a straightforward process that can be done by following a few simple steps. The fuel water separator is an important component of the fuel system, as it helps to remove water and other contaminants from the fuel before it enters the engine. Over time, the fuel water separator can become clogged or damaged, and it is recommended to replace it periodically to ensure the proper functioning of the engine. The replacement process typically involves unscrewing the old fuel water separator, cleaning the area, and installing a new fuel water separator, ensuring that the gasket is properly lubricated and the unit is tightened securely but not overtightened. It is also important to take necessary safety precautions when working with fuel, and some boaters recommend draining the fuel from the old separator and filling the new one before installation.

Unscrewing the fuel/water separator

• Gather the necessary tools and materials: You will need a truck filter wrench, clean rags, a new fuel/water separator filter, and a small amount of motor oil or Yamalube 2-stroke oil. It is also recommended to have a spent windshield washer fluid container or a similar catch pan to collect any fuel that may spill during the process.
• Prepare the work area: Before beginning, ensure that all electric components are turned off and that the boat's bilge access doors are open to allow proper ventilation and minimise the risk of igniting fuel vapours. Work with extreme caution when handling fuel, and avoid wearing synthetic clothing or jewellery that could create static electricity and potentially cause a spark.
• Draining and removal: If your fuel/water separator is mounted, you will need to drain it first. Place the catch pan under the filter housing and open the drain valve at the bottom of the filter to release any fuel. If your separator is not mounted, you can skip this step. Once drained, proceed to unscrewing the filter. Use the truck filter wrench to loosen the filter, turning it counter-clockwise. If the filter was over-tightened during the previous installation, you may need to apply some force, but be careful not to strip the threads.
• Cleaning and preparation: Once the old filter is removed, clean the area thoroughly with rags to remove any fuel residue or debris. Inspect the gasket surface and wipe it with a small amount of motor oil or Yamalube to ensure a proper seal when installing the new filter.
• Installing the new filter: Take the new fuel/water separator filter and fill it with fresh fuel. Be sure to only fill it near the top, leaving some space. Then, carefully thread the new filter into place by hand. Tighten it securely, but be careful not to over-tighten it. Once the new filter is in place, run the engine and check for any leaks. If no leaks are detected, you have successfully replaced the fuel/water separator.

Remember to dispose of the old filter and any spilled fuel properly, following local regulations and guidelines for hazardous waste disposal.

Whether to fill the new separator with gas

Whether or not to fill the new fuel water separator with gas is a topic of debate among boat owners. Some people say that pre-filling a boat's fuel water separator is a great habit, as it eliminates the introduction of a large amount of air into the fuel system, making the engine's fuel lift pump's job much easier. This can prevent air-locking the fuel pumps, which can cause damage to the injectors.

On the other hand, others argue that if there are no leaks in the fuel lines, the fuel pump should be able to suck fuel from the tank and purge out the air itself. This can serve as a self-test for air leaks in the fuel system.

Most people who pre-fill their fuel water separators do so to avoid the hassle of manually removing air from the fuel system in case the engine won't start after changing the filter. If you don't pre-fill the new separator, you may need to use a primer bulb to remove air from the system.

Ultimately, the decision of whether to fill the new fuel water separator with gas is up to the individual. Pre-filling can make it easier to get the engine started after changing the filter, but it is not strictly necessary, and the fuel pump should be able to purge out any air in the system.

How to remove the fuel filter

To remove the fuel filter, you will need to first drain the fuel from the filter. Place a catch pan under the filter housing and open the drain at the bottom of the filter. Once the filter is drained, you can start to remove it.

If your fuel filter is mounted on the engine, you will need to remove the hoses from the metal bracket and unbolt the bracket to remove the entire assembly. This will give you more space to work with and make it easier to access the filter.

If your fuel filter has a plastic cup, it may be difficult to remove with pliers as the ethanol fuel can cause the plastic to expand. In this case, it is recommended to place the entire assembly in the freezer for 30 minutes to cause the cup to shrink, making it easier to remove by hand. Be careful not to cross-thread when reinstalling the new filter.

If your fuel filter has a bowl, you can remove it by hand or with a strap wrench. Wrapping a length of neoprene around the bowl can provide a better grip and help protect the surface. Remember to wipe the gasket contact surface with oil or Yamalube before reinstalling.

When removing the fuel filter, be very careful when working around fuel. It is also important not to over-tighten the new filter. Tighten it by hand, as per the specifications, and only use tools to spin it until contact.

Whether gas will spill out if the separator is removed

Replacing the Fuel Water Separator on an Outboard

The fuel water separator on an outboard engine should be replaced periodically to ensure the system remains free from gunk and choke-offs. This task can be done at home and requires only a few hours to complete.

Will Gas Spill Out?

When removing the fuel water separator, gas will not spill out if the tank is lower than the motor. It is important to note that gas will not siphon out of the tank as long as the anti-siphon valve is functioning properly. However, clamping the line from the tank to the filter mount with a C-clamp before removal can provide added security as a precaution.

Step-by-Step Guide to Replacing the Fuel Water Separator:

Step 1: Open hatches to ensure proper ventilation. Close the fuel valve at the tank and cut the supply hose at the mounting location, draining the contents. Alternatively, you can plug the line by inserting a bolt and securing it with a hose clamp.

Step 2: Remove the old fuel water separator. This can be done by simply unscrewing it, but be careful not to over-tighten when reinstalling the new one. Putting a small amount of oil on the new filter/gasket before screwing it on is recommended.

Step 3: Install the new fuel water separator. The head unit should be installed vertically, above bilge water, between the tank and the engine. Ensure that the hoses reach the engine and tank without kinking or making sharp turns. Drill pilot holes, inject sealant, and fasten with self-tapping stainless steel screws.

Step 4: Use sealant and smear motor oil. Apply sealant on the threads when installing the fuel filter's fittings. Also, smear some motor oil on the gaskets or O-rings for the element and the inspection bowl.

Step 5: Attach and clamp the hoses. Attach the hose from the tank to the "in" port and from the engine to the "out" port. Double-clamp firmly to secure the hoses, but be careful not to pinch them.

Step 6: Start the engine and check for leaks. After installation, start the engine and check for leaks at a fast idle. It is recommended to sea-trial the system close to home at high RPM, keeping a close eye for any leaks.

By following these steps and taking the necessary precautions, you can replace your fuel water separator effectively and avoid any gas spillage during the process.

How often to change the separator

The frequency with which you should change the fuel water separator on your outboard engine depends on a few factors. Firstly, it depends on how many hours the engine has been in operation. Some manufacturers, such as Yamaha, recommend changing the fuel water separator every 50 hours of operation. However, if you don't operate your boat frequently, you may prefer to change it annually or every 12 months. This is because, over time, fuel can turn to varnish, and condensation can build up in the fuel tank, especially if it is not kept full. Therefore, it is recommended to change the separator at least once a year, especially if the boat is used seasonally and the engine is not run for several months.

Another factor to consider is the quality of the fuel being used. If the fuel is contaminated with water or debris, the separator will fill up more quickly and need to be changed more often. It is a good idea to inspect the separator regularly, especially after periods of inactivity, to check for the presence of water. This can be done by draining the separator into a clear container and allowing the contents to separate, or by installing a clear bowl-type separator with a drain valve. If water is present, it should be drained immediately, as water can cause serious damage to the engine if it gets into the fuel system.

In addition to regular inspections and separator changes, it is also recommended to use a fuel stabilizer and an additive such as SeaFoam or Yamalube to help prevent water contamination and keep the fuel system clean.

Frequently asked questions