5.7 long block replacement - elec fuel pump conversion

[Deep cove marine]

Hello, thank you for looking, my company does not deal in mercruiser but due to a mistake made by one of my technicians I had to replace the engine block on an an incorrectly winterized 5.7. The old engine had a mechanical fuel pump, and when the new long block arrived it did not have the aperture for the actuating rod to utilize a mechanical fuel pump. I went with a refutable mercruiser dealer, Davey Marine in Florida, who supplied me with the electric fuel pump and the various components to do the conversion, I wired it in with a 20 amp inline fuse off the 12 volt keyed input to the coil per there instruction.

when I turn the key to the on position the fuel pump starts and stays running regardless of whether or not the engine is running, my question is, is that normal? Seems to me it should be connected to an oil pressure switch, or some other pressure switch so that it could be deenergized after it has produced the appropriate amount of pressure? I really appreciate anyone's input with more experience with this than I have. Thank you for your time.

 

[Bt Doctur]

Not normal, you need the pressure switch Standard PS-64

 

[achris]

. I wired it in with a 20 amp inline fuse off the 12 volt keyed input to the coil per there instruction....

The electric fuel pump is powered from 2 sources. During 'run' it get power from the switched 12v (purple) wire VIA an oil pressure switch. This switch is N.O., and closes when the engine has oil pressure. The other power source for the pump is the ' I ' post on the starter motor solenoid. This powers the pump while the engine is cranking, before oil pressure closes the pressure switch. This is the standard wiring as per Mercruiser original spec. But, it has the drawback of running the full current required by the pump through the switch, not ideal. The alternative is to use a relay, we all prefer the relay. Below is the standard Merc diagram, with the unofficial iboats forum team modification.

Chris.......