Outboard Engine Fuel and Oil Components

Boat Motor Fuel and Oil Components Resources and Information

Outboard fuel and oil components are necessary for performing periodic service and repairs on your outboard engine. PartsVu offers a complete selection of these essential components, including outboard engine fuel and oil filters, filter wrenches, primer bulbs, drain plugs, fuel and oil pumps, and carburetors and carburetor repair kits.

Looking for more products for your outboard or boat? Shop PartsVu’s parts and accessories and aftermarket parts, or shop our outboard engine fuel and oil components by category, including: 

• Fuel Filters, Wrenches & Primer Bulbs
• Oil Filters, Drain Plugs, and Wrenches
• Fuel and Oil Pumps
• Carburetors and Carburetor Repair Kits
• Fuel Filters

Outboard Engine Fuel and Oil Components FAQs

Why are there so many fuel filters?

The answer is simple yet complex. All dirt is not created equally – dirt appears in various forms and sizes. Some dirt particles are larger pieces, and some are minute dust particles. Some material you can easily see, other material can be microscopic biological growth and may still be growing.

Dirt takes different forms. It may be shaped like a ball or more like an arrow. The ball type usually gets caught easily, but the arrow type may penetrate the first and second filter and get stuck in the third. Once the arrow lays across the filtering medium, it partially closes the passage holes and makes them smaller, capturing even smaller debris. The clogging will then continue. If the initial filter really becomes restricted, the vacuum on the filter may suck the debris through it and on to the next filter, and so on.

This filter helps separate water from fuel and also helps keep debris out. It is recommended to change this filter every 50 hours. We also recommend carrying a spare fuel-water separating filter on board in case you get a tank of bad gas, and the filter is overwhelmed.

This filter is attached to the electric fuel pump in the VST and filters gas again just before it’s pressurized into the fuel injection rail(s). The VST is a prime spot in the fuel system where deposits and gum can form, particularly if fuel is untreated. Protect this filter by consistently treating every tank of fuel with Ring Free Plus and regularly inspect and service the first two filters in the fuel line. Refer to the specific engine’s service manual for the recommended service interval and the exact location of the filter.

This fuel filter is typically on the front, side, or rear of the powerhead, and is usually made of plastic you can see through. It filters fuel coming into the outboard. This “primary” filter usually features a small water trap at the bottom of the cup. This is the first filter after the 10-micron filter, so if there’s water in here, it’s time to change your 10-micron. On outboards, there may be a red ring visible inside this filter. Don’t ever remove it. If it’s floating, you’ve got water in this filter’s trap and it time for a change.

Some models have an in-line filter between the primary fuel pump and the VST (vapor separator tank) and/or in the fuel line between the VST and the fuel rail, located along the top of the outboard. Refer to your service manual or contact your dealer for the exact location for your model.

How do I perform an oil change on my 4-stroke outboard engine? 

Spent engine oil can be removed from the engine by extraction or via the oil pan drain screw plug. The extraction method requires the use of a vacuum extractor which is inserted down the dipstick tube and uses suction to pull the spent oil from the pan. Oil extraction tends to be very clean and is probably the most widely used among marine technicians. Alternatively, the drain screw itself can be removed. Be sure to have plenty of drain pan capacity as some engines can hold up to seven quarts of oil. We also recommend an oil absorbent pad like the 3M HP156 pad to catch any errant drips that might soil your driveway or lawn.

In cold climates, it may be helpful to start and warm the engine before draining the oil to thin it slightly. However, if possible, perform the engine oil change as the first part of the service since the maximum amount of oil will be in the oil pan already from the engine sitting allowing you to extract as much old oil as possible to minimize contamination of your fresh oil.

As the old oil is draining, you can work on removing the engine oil filter. Depending on your specific model, your filter may have a drain lip that helps to keep the mess to a minimum when you unscrew the old filter. However, most older engines do not have this feature. We suggest being prepared with plenty of absorbent rags or placing a small cup that is cut to size below the filter before removal. Using a PartsVu Maintenance Essentials filter wrench is the best way to loosen the filter. Remember when you reinstall the filter, over-tightening will only make your life more difficult when you are ready for the next service. Some technicians puncture the old filter allowing trapped oil to drain back into the block before removal, but this will ruin your ability to take the filter apart for further inspection.

Several laboratories provide performance testing of used oils, allowing you to learn more about the health of your engine. Blackstone Labs is one such provider, and they have a convenient mail-in kit that includes everything you need to submit an oil sample. They can also test gear oils, hydraulic fluids, and oils from your other vehicles or toys. Oil test results can tip you off to an accelerated wear condition inside of your engine long before any other symptoms show up. If you still want to know more about your engine, purchase an oil filter cutter and open the spent filter to look for evidence of contamination and metal dust or shavings.

Once you have inspected your spent oil and filter, set them aside for proper disposal. If you removed the drain screw to empty your oil, carefully reinstall the drain plug. The new oil filter should be removed from its package and the o-ring lubricated with a thin coat of fresh engine oil. Spin on the new oil filter and gently tighten to seat the o-ring without over-torquing.

 Marine offers a wide assortment of engine oil – both in blend and viscosity. If you are uncertain as to which oil is best for your application, consult your owners’ manual. Loosen the yellow oil fill plug on the top of the engine and pour in fresh oil. We recommend adding slightly less than the stated capacity. With the engine trimmed down, check the oil level on the dipstick after allowing a few minutes for the oil to drain into the oil pan properly. Filling the oil to the lower level on the dipstick will help you to measure if the oil level changes over time with the engine in operation.

How do I service my 4-stoke outboard engine’s fuel system? 

Use a filter wrench to loosen the existing filter element and use caution when removing it as it will be filled with gasoline. A clear plastic or glass container is helpful to dump the filter and examine the contents. A small amount of debris is common, as is a small amount of water after the fuel has had a moment to settle. More significant amounts of water would warrant further investigation.

If your filter’s mounting location allows it, pre-fill the replacement filter with some gasoline to make re-priming the fuel system easier. It is also advisable to use a small amount of grease or engine oil to lubricate the o-ring before installation. Spin on and hand tighten only about a half turn to snug.

Move back to the engine and locate the filter element(s) on the engine. The scope of this service will only include the low-pressure fuel filter and fuel water separator if applicable by model. recommends that owners do not service their high-pressure fuel filters. Depending on your engine model, the water separator filter (or castle filter) may be removed by using a wrench, standard tools, and a little caution. Unplug the water-in-fuel sensor if applicable and spin the cap off of the housing. Replace the filter element with a fresh one, lube the o-ring with grease or oil, and carefully reinstall the cap.

For most other models, the low-pressure fuel filter is inline where the fuel supply line passes down the side of the cowling. On applicable models, locate the Schrader valve on the fuel system. Cover the valve with a rag or towel and depress the valve stem to vent the pressure from the system before service. With the pressure vented, remove the inline filter and replace it with a new one paying particular attention to locate the clamps or zip ties securing the hoses to the filter.

Locate your engine’s primer bulb if applicable and use the primer to pump up the fuel system. You should feel and hear gasoline entering and filling the filter cup. Check for leaks and prime until the bulb becomes firm.

If you are not already regularly running Quickare and/or Quickleen through your fuel system, the 100-hour service interval is an excellent time for a “shock treatment.” Quickare is a fuel system cleaner and top-lube that will help to clean deposits from the tank, lines, carburetors, injectors, and pumps. It breaks up fuel system varnish and will help to prevent gumming.

Quickleen is a fuel system conditioner that also helps to remove carbon deposits. The standard dose is one ounce per ten gallons, but if you are not running the product regularly, you can double that ratio for more cleaning power. Pour the products into the fuel tank fill and run the boat. No additional work is needed. It is a great idea to inspect your fuel tank fill’s o-ring for damage when you add fuel or additives as a damaged o-ring can allow water from rain or boat washing into your fuel system.