When To Change Your Mercruiser Inline Fuel Filter

The fuel filter on a Mercruiser sterndrive or inboard gasoline engine should be changed annually, or after every 100 hours of operation. This is because any water trapped in the filter could corrode the filter canister over the offseason. It is recommended to start the next boating season with a fresh filter. Some people change their spin-on fuel filters at the beginning of each season, and if you are having water problems in your gas, you may need to change it more often.

Fuel filter replacement frequency

The fuel filter on a Mercruiser sterndrive or inboard gasoline engine should be replaced annually or after every 100 hours of operation. For many boat owners, changing the fuel filter is part of an annual service performed before winter or offseason lay-up, along with an engine oil-and-filter change and fuel treatment.

If you are having water problems in your gas, you may need to change the filter more often. It is also recommended to schedule another fuel filter replacement after your next boating trip if you notice a large amount of dirt or water in your old fuel filter.

The frequency of replacement also depends on the type of fuel filter you have. If it is a spin-on (similar to an oil filter), it should be changed at the beginning of each season. If it is a metal can filter, it should be changed at least annually, and maybe more often as they are finer and smaller.

Water in the gas tank

If you are experiencing issues with water in your gas tank, it is important to check and replace your fuel filter regularly. It is recommended to replace your fuel filter every season or sooner if needed, especially if you are having problems with water in your gas. When replacing the fuel filter, make sure to inspect the old fuel for any signs of water or debris. If there is a significant amount of water present, schedule another fuel filter replacement after your next boating trip.

• Keep spare filters and a filter wrench on board.
• Use a marker to write the replacement date on the fuel filter.
• Avoid sparks or open flames when working with fuel.
• Work in a well-ventilated area and avoid skin contact with fuel.
• Absorbent towels can help catch any spilled fuel during the replacement process.

Fuel filter replacement process

The fuel filter in your vehicle keeps dirt, rust, paint chips, and other contaminants from entering the fuel injectors and damaging the engine. It is recommended to replace the fuel filter in your vehicle every two years or 30,000 miles. Here is a step-by-step guide on how to replace your fuel filter:

Step 1: Relieve Fuel Pressure

First, locate the fuse or relay for your vehicle's fuel pump and unplug it. Try to start the vehicle; if you have disconnected the correct circuit, the engine will turn over but not start. Shut off the engine and let it cool if it has been running.

Step 2: Find the Fuel Filter

Check an auto repair manual to locate your vehicle's fuel filter. Remove the replacement fuel filter from its box.

Step 3: Disconnect and Remove the Old Filter

Put on safety glasses. If your filter is housed underneath your vehicle, drive it up on ramps to get extra clearance. Position a drain pan under the filter. Find, loosen, and remove the fuel lines connected to either end of the filter. You may need to use pliers to remove retaining clips from the ends of the lines. Loosen the screw clamp or bolts holding the fuel filter in position, then remove the filter and place it to one side.

Step 4: Install the New Filter

Put the new filter in position and tighten or clip it into place. Ensure it is facing the correct way, as fuel is meant to flow only one way through a filter. Look for an arrow on the filter body indicating the direction of flow and orient the filter so the arrow points toward the engine.

Step 5: Reinstall the Fuse or Relay

Reinstall the fuel pump fuse or relay that you disconnected earlier. Try starting the vehicle. If it runs normally and there is no fuel leaking from the new filter, you are done.

Additional Tips:

• Keep a spare filter and filter wrench on board.
• Write the replacement date on the fuel filter with a marker.
• Avoid sparks or open flames when working on the fuel filter.
• Work outside with adequate ventilation.
• Avoid skin contact with fuel, as it can cause injury.

Fuel filter bracket inspection

To inspect your fuel filter bracket, you will first need to locate your fuel filter. On most cars, it will be in line (placed between two sections of the fuel line), usually under the car near the fuel tank. It will look like a small cylinder.

• Turn off your battery switches or disconnect the boat's batteries.
• Turn off your fuel supply valve (if equipped).
• Position a fan to ventilate the bilge and work area.
• Place some absorbent towels under the filter to catch any spilled fuel.
• Using a fuel filter wrench, remove the old fuel filter.
• Inspect the filter mount bracket to ensure that the old filter O-Ring has been removed.
• Wipe clean the filter bracket and inspect the surfaces where the O-ring will have to seal.
• Replace any damaged filter brackets.

It is important to note that fuel filters should be replaced regularly, with some sources recommending replacement every two years or 24,000 miles, or at least annually, especially if there are water problems in the gas. Additionally, if your car seems to be losing power or stalling, especially when you press the accelerator, it may be due to a problem with your fuel filter.

Fuel filter wrench

A fuel filter wrench is an essential tool for removing and installing fuel filters. It is recommended to have a separate fuel filter wrench and oil filter wrench to prevent spilled fuel and contaminated oil from mixing or entering separate systems.

There are various fuel filter wrenches available for Mercruiser engines, with some designed for specific engine models. For example, the Quicksilver 896661 Fuel Filter Cap Removal/Installation Tool is suitable for 75-450hp Mercury Outboards, while the Quicksilver/Mercury Oil Filter Wrench 91-802653Q02 is designed for Mercury/Mariner Four-Stroke Outboards with 9.9 to 60 hp.

When purchasing a fuel filter wrench, it is important to ensure it is the correct size and type for your engine. Adjustable filter wrenches are available, but using a fitted OEM filter wrench can help prevent slippage, over-torquing, and shearing off threads that may cause leaks.

In addition to a fuel filter wrench, other tools that may be useful for boat maintenance include absorbent towels, a cup wrench, a clear container for examining fuel, and a small amount of grease to lubricate the O-ring.

Frequently asked questions