Mercury – Fuel Pump | MerCruiser Sterndrives | 42725A3

Overview

If you’ve spent any time working on the old 2.5L, 3.0L, or 3.7L MerCruiser sterndrives, you know the mechanical fuel pump is one of those parts that slowly fades rather than suddenly fails. The engine starts getting picky—harder to start, a stumble when you crack the throttle, or it just runs out of breath when you’re trying to get on plane. This pump is the proper replacement for the versions with the filter bowl pointing down. It bolts in the same place, lines up with the stock fittings, and gets fuel moving the way these simple carbureted motors were built to run.

Key Features

 • Built for 2.5L, 3.0L, and 3.7L MerCruisers – Matches the downward-facing bowl setup exactly.
 • Steady Fuel Pressure – Helps bring back smoother starts and cleaner throttle response.
 • Marine-Tough Construction – Made to handle bilge heat, vibration, and constant engine shake.
 • OEM Fit & Function – No strange threads, no alignment surprises—just a proper match.
 • Works with Stock Filter Bowl – Designed to reuse the original bowl unless it’s damaged.

Engine & Boat Compatibility

 • MerCruiser 2.5L
 • MerCruiser 3.0L
 • MerCruiser 3.7L
 • Carbureted sterndrives with downward-facing bowl

Performance & Practical Benefits

A healthy pump brings these engines back to life. Cold starts aren’t such a chore, the engine doesn’t fall flat when you throttle up, and it handles chop and turns better because the fuel delivery is steady again. If your boat’s been stumbling or just feeling tired, the pump is often the quiet culprit—and swapping it usually makes the boat feel “right” again.

Why Buy OEM

With OEM parts, you know the pump will deliver the pressure these engines were designed around. Aftermarket pumps can be hit-or-miss—some run weak, some don’t last long in the heat of a bilge. OEM gives you consistent flow, proper fitment, and fewer headaches.

FAQ

Q1: What are the telltale signs my pump is wearing out?
A: Long cranking, hesitation when you throttle up, or the engine sagging under load.

Q2: Do I need to replace the filter bowl too?
A: Only if it’s cracked or damaged—the pump is made to reuse your original bowl.

Q3: Is this a driveway-friendly job?
A: For most boaters, yes. A few wrenches and patience usually get it done.

Q4: Will I notice a difference right away?
A: Most of the time, absolutely. Carbureted MerCruisers respond quickly to a strong pump.

Q5: Safe to run with ethanol-blended fuel?
A: Yes—this pump is built for modern marine fuels.

• Supersessions
  861676A1, 861676T09, 8M0073435, 8M0073435