T-H Marine Oil & Fuel System Components & Accessories

T-H Marine Oil & Fuel System Parts and Products Resources and Information

T-H Marine is one of the most trusted names in the boating industry. PartsVu is thrilled to offer a selection of high-quality genuine T-H Marine oil and fuel system components and accessories to match your outboard marine motor’s exact specifications. Need help servicing your outboard fuel system? Check out this guide over on our blog, where we regularly publish how-tos and other helpful resources. 

Browse PartsVu’s broad selection of marine products and accessories, shop more T-H Marine boating products or browse T-H Marine oil and fuel system components and accessories by category, including:

• Fuel Filters
• Motor Flushers
• Motor Connectors, Fuel Fittings, & Plugs
• Gear Lube & Oil Change Essentials

T-H Marine Oil & Fuel System Components & Accessories FAQs

How do I service my 4-stroke outboard 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. Mercury 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.

How do I service my 2-stroke outboard 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. Mercury 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 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.

How do I choose the right marine fuel for my outboard engine? 

Using the right marine fuel for your boat’s engine is essential for reliable and optimal performance on the water.

Because different makes and models of boat engines require different fuels, using the wrong boat fuel can cause significant damage to internal engine components as well as your boat’s fuel system.

For many boat owners, it’s common to feel a bit unsure as to which type of marine fuel is right for their engine(s). Choosing between different ethanol levels, mixing oil with fuel, and even using diesel can be downright confusing.

Ethanol-free gasoline is produced in a few different octane levels. REC-90 is marketed for boaters and for use in other small engines. It’s an ethanol-free, 90-octane unleaded gasoline blend designed for use in marine and small engines that ethanol found in other gasoline blends can damage.

Ethanol-free gasoline does not come with the corrosive effects of gasoline containing ethanol. You can expect the best performance and lifespan of your boat’s engine from this type of boat gas.

As one of the most widely-available and inexpensive marine fuels, E10 is safe for most boat engines. E10 stands for “10% ethanol content” gasoline. Ethanol was introduced to reduce hydrocarbon emission pollution without substantially affecting performance.

What is the Problem with Ethanol in Marine Fuel?

As a general rule, avoid marine fuel with ethanol or high-ethanol content (anything above 10% ethanol) whenever possible.

Ethanol attracts water and moisture from the air through the fuel tank vent system. This happens due to a process called “phase separation.” When this moisture accumulates at the bottom of the fuel tank or throughout the fuel system, the engine’s performance is dramatically reduced, corrosion forms through oxidizing internal components, and dilutes the gasoline.

To prevent phase separation, boaters have a few methods:

• Install a 10-micron water-separating fuel filter between the fuel tank and the boat engine to keep water and other contaminants out.
• Use a fuel stabilizer in every tank of fuel, either when storing the boat long-term or between fill-ups.

Can you use regular gas in boats?

The answer to this question is both yes and no:

• Yes, you can use the same gasoline as a car in your boat engines; however, this fuel must be E10 or ethanol-free gasoline. E15 or gasoline with higher levels of ethanol is not recommended.
• Marine fuel for smaller outboard or 2-stroke outboard engines often requires a gasoline and oil mixture, which requires knowing the right ratios.

Above all, make sure that you pay attention to what is available at the pump. Using the wrong gasoline – even in a pinch – can lead to serious damage and performance issues, all of which can be avoided by using appropriate fuel. Last, if you don’t trust a gas station’s gas or it’s not clearly labeled, avoid using it at all.