How do I know if my outboard fuel pump is bad?
The symptoms of a bad fuel pump on a boat are engine sputtering at high speeds, poor acceleration under heavy loads, increased fuel consumption, increased engine temperatures, and the engine sounds rough (whine). If you see one of those symptoms, your fuel pump might be causing those problems.
How do you test a fuel pump on an outboard motor?
Connect your fuel pressure gauge to the pulse hose. Crank the engine. Normal fuel pumps will put out between five and seven PSI. Readings below this point to a bad diaphragm or pump check valve.
How do you test a boat fuel pump?
How to Test an Outboard Fuel Pump
- Turn off your main electrical cutoff switch that governs motor ignition.
- Screw a compression gauge hose into the spark plug hole.
- Refer to your owner’s manual for the correct psi your engine needs.
- Check to make sure you have enough gas in the tank to be picked up by the sump.
What is a VST on a Mercury outboard?
VST stands for Vapor Separator Tank, FSM stands for Fuel Supply Module. These contain the high pressure fuel pump that builds your engines fuel pressure.
How do I know if my Mercury fuel pump is bad?
What are the symptoms of a bad fuel pump on an outboard motor?
- Silence. When you try to start your engine, you should be able to hear the sound of the fuel pump engaging.
- Slowing, Stopping, or Sputtering.
- Gas Guzzling.
- Heat.
- One-Way Valves.
- Diaphragm.
- Fuel Stabilizers.
Should primer bulb stay hard?
It usually goes soft after a couple hours just sitting there. It’s a brand new primer bulb and fuel line too. The primer bulb ensures the carburetors are full and the fuel pump is ready for fuel delivery. Staying pressurized is not a requirement for Easy starting.
What does the air compressor pump on a Mercury Optimax do?
This air compressor pump is basically a dead single cylinder being drug along for the ride to push air and fuel into the direct inject chamber (also called parasitic drag). This is an awesome design however; nothing is free. It takes 20 hp to run that pump.
What’s the rev limit on a Mercury 300X?
The 300X, by a long shot. They could have called it a 325X. The rev limit on the XS is 6400 while the X spins to 7000. After testing, the 300X made exactly 326 hp stock with the XS making 306 hp.
How many horsepower does a Mercury Optimax 300X have?
After testing, the 300X made exactly 326 hp stock with the XS making 306 hp. They both made over 300 ft lb of torque however the X rev’d to 7000 with more after peak power (over-rev) than the larger displacement XS. This explains the larger top speed numbers we have all seen from the X.
What causes a fuel pump to stop working?
The inner rubber diaphragm can develop cracks or pin holes that effect proper fuel flow, and inner check valves and springs can break causing complete pump failure. Older motors can have pre-ethanol components that should be upgraded to new ethanol resistant materials. Need other parts?