Electric fuel pump Installation-Priming???

[kmadsen]

I'm replacing the electric fuel pump on my '93 OMC Cobra 262/4.3L. Engine always started without fail previously, and after some troubleshooting narrowed it down to fuel pump (Engine ran about 15-20 seconds depleting float bowl and died) No fuel pumping out into carb throat when I crank the starter and good voltage to pump. Also, i feel no vibration from pump when I crank the starter.My question is, How best to prime pump or do I even need to prime the pump during installation? Any other tips are appreciated. If you think I missed anything please let me know. Thanks

 

[Don S]

Re: Electric fuel pump Installation-Priming???

Just make sure the filter is full. If you are installing a new pump, I would suggest you also replace the filter. But, before you do, dump it's contents out and see if there is any water in it. If there is a LOT of water, that is one of the things that will take out a fuel pump. The other is air. anything over 10 seconds of running dry (Cranking the engine with no fuel) can damage the pump.
Just fill the new filter with some clean gas and install it. It will prime from there.

 

[kmadsen]

Re: Electric fuel pump Installation-Priming???

Don S. Thanks for a quick reply, I've read some of your previous posts and even "snap-shot" the fuel pump,oil pressure sensor, starter etc wiring diagram you posted for another forum trekkie. Can't tell you how great it is to be able to find help. I'll make sure all my wiring connections are up to par and follow your advise. hopefully i can return the favor at a later date. ( o Y o )

 

[Don S]

Re: Electric fuel pump Installation-Priming???

Just understand one thing, you may not have a fuel pump problem. Your engine doesn't have an oil pressure switch to control the pump. I'm fairly sure you have diodes controlling the fuel pump from the starter relay and the alternator. So don't be surprised if it will still start and run for 20 seconds with the new pump.

 

[kmadsen]

Re: Electric fuel pump Installation-Priming???

Thanks Don, but I checked for voltage from the relay to the plugin to the fuel pump and was getting 11.8 volts when I cranked the starter. Shouldn't that negate any faults or problem with diodes?

 

[Out of Bounds]

Re: Electric fuel pump Installation-Priming???

You also should check the check ball in the fitting in the top of the gas tank. We are seeing alot of different boats having the gas casuing the sping and ball to stick and not let the fuel out of the tank.

 

[kmadsen]

Re: Electric fuel pump Installation-Priming???

I understand what Don S. was saying, The fuel pump gets power from starter circuit to start engine, but then gets power from diodes thru power bus once engine is running. The engine started only once, using fuel remaining in carb bowl, and never started again. I put a little suction thru line from fuel tank and got fuel, so it wasn't the ball valve in tank. No water in filter, replaced fuel pump and it runs like a charm. Lucky me. ( o Y o )