Sierra 18-7844 Fuel Filter, Short 3.875 Inch, 21 Micron, Replaces Mercury 35-807172

The Sierra 18-7844 is a 21 micron fuel filter built in the short, 3.875 inch length to fit engines that call for the compact filter body. Ethanol-blended fuel absorbs more water and loosens more particulate than non-ethanol fuel, so proper filtration ahead of the carburetor or injectors is essential to protect the fuel system on any horsepower of engine. This filter is rated to flow 90 gallons per hour, giving even high-demand motors an unrestricted supply of clean fuel while trapping water and debris before they reach the engine.

The filter housing is built with a plastic outer body and is designed as a direct replacement for the Mercury Marine 35-807172 filter. It is a straightforward drop-in service part: remove the old canister-style filter and thread on the Sierra 18-7844 in its place. Keeping fuel filtration current is one of the simplest ways to prevent hard starting, rough running, and fuel-related damage caused by water contamination or loosened ethanol deposits.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-7844
• Filter Length: Short - 3.875 inches
• Filtration Rating: 21 Micron
• Flow Rate: 90 gallons per hour
• Outer Material: Plastic
• Weight: 0.98 pounds
• Unit Count: 1 filter
• Vehicle Service Type: Personal Watercraft
• OEM Cross Reference: Mercury Marine 35-807172, Mercury Marine 35-802893Q

Fitment

Fits applications using the short, 3.875 inch 21 micron canister-style fuel filter, including personal watercraft applications specified by the OEM cross-reference numbers below.

Replaces (OEM)

• Mercury Marine 35-807172
• Mercury Marine 35-802893Q

Frequently Asked Questions

What does the Sierra 18-7844 fuel filter replace? The Sierra 18-7844 is a direct replacement for the Mercury Marine 35-807172 and Mercury Marine 35-802893Q fuel filters.

What micron rating is this filter? The Sierra 18-7844 is rated at 21 microns, which traps water and particulate loosened by ethanol-blended fuel before it reaches the engine.

How long is the Sierra 18-7844 filter? It is the short-length version at 3.875 inches, as opposed to the long 4.35 inch version sold under a different part number.

What flow rate does this filter support? The Sierra 18-7844 flows at 90 gallons per hour, which is sufficient to feed high-horsepower engines without restricting fuel delivery.

What is the filter housing made of? The Sierra 18-7844 has a plastic outer housing.

How much does the Sierra 18-7844 weigh? This filter weighs 0.98 pounds.

Is the Sierra 18-7844 a genuine Mercury part or an aftermarket replacement? The 18-7844 is a Sierra-manufactured aftermarket filter engineered to replace the Mercury Marine 35-807172 and 35-802893Q filters with equivalent filtration and flow performance.

Why does ethanol-blended fuel need extra filtration? Ethanol-blended fuel absorbs more water and loosens more particulate than non-ethanol fuel, which is why a properly rated filter like the 21 micron Sierra 18-7844 is important for protecting the fuel system.

How many filters come in the package? The Sierra 18-7844 is sold as a single fuel filter, one unit count per package.

What is the difference between the 18-7844 and the 18-7845? The 18-7844 is the short 3.875 inch version, while the 18-7845 is the long 4.35 inch version of the same 21 micron filter line; be sure to order the length that matches your existing filter housing.

What type of engines is the Sierra 18-7844 designed for? This filter is designed for use with personal watercraft and other engines that use the short, 3.875 inch 21 micron canister-style fuel filter, including applications originally fitted with the Mercury Marine 35-807172.