Installing electric fuel pump

[Erock]

I am istalling an electric fuel pump on my boat and I'm trying to figure out the best way to wire it up. I know it should be wired to my oil pressure sender for power only while the engine is running, but what about during cranking? I was going to run a wire from the hot in start position on my ignition switch and use a relay to power the pump while cranking. That would power the pump while cranking and then when the engine started the oil pressure sender would take over when the key was released from the start position. Is this correct thinking? Also can I leave the mechanical pump in place and just put plugs in the fitting holes or should it be removed and the blocked off? Any help would be greatly appreciated. Thanks.

 

[Don S]

Re: Installing electric fuel pump

Merc picks up the power to the pump while cranking from the starter solenoid. In the drawing below, it's the purple/yellow wire.

 

[jerryjerry05]

Re: Installing electric fuel pump

Don't use a regular automotive pump.They sell a marine version that the Coast Guard approves.
Regular auto isin't spark proof.Dangerous.
The one Don showed in his photo.is a marine type.J

 

[zbnutcase]

Re: Installing electric fuel pump

And its wired through an oil pressure switch, not the sender!

 

[Erock]

Re: Installing electric fuel pump

I don't think there is a switch on my engine. Can I T one in behind the sender on the side of the engine? Where would it be located on a 2.5 Merc? (I mean the switch if there is one.)

 

[bruceb58]

Re: Installing electric fuel pump

Yes, you can tee it off. Just make sure that vibration won't be an issue and it breaks the tee after time.

Any reason you just don't stick with the mechanical? That is what I would do.