RPS Mechanical Fuel Pump for MerCruiser OMC Volvo Penta 2.5L-3.7L — Filter-Bowl-Down, Gasket Included

RPS Mechanical Fuel Pump is a direct-fit replacement for MerCruiser, OMC and Volvo Penta 4-cylinder marine engines (2.5L, 3.0L, 3.7L) with a downward-facing filter bowl, restoring reliable fuel delivery and leak-free mounting.

This RPS pump is engineered to match OEM dimensions and function for a wide range of GM-based inline 4-cylinder marine engines used in boats from the early 1980s to current production blocks. It replaces common factory part numbers including 8M0073435, 861676A1, 42725A3, 509407, 3854858 and Sierra items 18-7282 and 18-35437. The unit’s filter-bowl-down orientation (inlet at 2 o'clock, outlet at 3 o'clock) and supplied gasket make it suitable for direct swap-ins where the original pump used the same layout.

How do I confirm this pump will fit my engine?

Begin by checking your current pump’s overall shape, mounting bolt pattern and the orientation of the fuel filter bowl. This RPS pump is designed for GM-based 2.5L (153 CID), 3.0L (181 CID) and 3.7L (224 CID) inline 4-cylinder MerCruiser, OMC and Volvo Penta engines; physical verification ensures correct alignment of inlet/outlet and mounting holes.

• Compare bolt hole spacing and flange shape to the existing pump.
• Verify filter bowl points downward; inlet at 2 o'clock, outlet at 3 o'clock.
• Cross-check OEM numbers: 8M0073435, 861676A1, 3854858, Sierra 18-7282/18-35437.
• Confirm engine displacement 2.5L, 3.0L or 3.7L inline 4-cylinder.

What performance should I expect after installation?

When installed correctly, this mechanical pump restores the expected fuel pressure range for carbureted marine engines, helping to eliminate hard starts and intermittent stalling caused by weak fuel delivery. The pump uses marine-grade materials intended to withstand humid, salty environments commonly encountered in boating.

• Delivers target fuel pressure suitable for carburetors (approx. 6–8 PSI).
• Durable construction resists corrosion in marine use.
• Filter bowl design helps trap debris before the carburetor.
• Supplied gasket helps prevent leaks at the mounting flange.

How straightforward is the installation process?

Installation follows standard mechanical fuel pump replacement steps and is typically straightforward for anyone familiar with small engine plumbing. A basic set of hand tools, clean rags, and a moment to depressurize and drain residual fuel will prepare the job; the included gasket reduces the need for additional sealants.

• Shut off fuel and remove old pump; note hose positions and fastener locations.
• Clean mating surfaces before fitting the new gasket and pump.
• Torque mounting bolts to factory specs and reconnect hoses securely.
• Prime the system and check for leaks before starting the engine.

Which parts and engines does this RPS pump replace?

This pump is intended as a direct replacement for a number of factory and aftermarket part numbers, matching the form, fit and function of the originals. It covers many GM inline 4-cylinder marine applications for MerCruiser, OMC and Volvo Penta engines where a downward filter bowl orientation is used.

• Replaces OEM numbers: 8M0073435, 861676A1, 42725A3, 509407, 3854858.
• Compatible with Sierra: 18-7282 and 18-35437.
• Designed for 2.5L, 3.0L, 3.7L inline 4-cylinder marine engines.
• Filter bowl down configuration—verify before ordering.

Who this is for: Boat owners, marine technicians and DIY mechanics who operate MerCruiser, OMC or Volvo Penta inline 4-cylinder engines and need a reliable, direct-fit mechanical fuel pump with a downward-facing filter bowl. If your engine requires the listed OEM or Sierra part numbers and uses a filter-bowl-down layout, this RPS pump and included gasket provide a practical replacement to restore proper fuel delivery and reduce downtime.