Electric fuel pump wiring with safety pressure switch

[jdogonhood]

Help. I'm trying to wire my new electric fuel pump to the new pressure switch on my 88' 4.3 omc. The safety switch has 3 prongs P, I,S. The fuel pump has two wires. The directions state to attach the red power pump to the P terminal and then ground the black pump to the block. My question is where does the existing light blue wire go from the old oil pressure sending unit ?, and what wires go to the I, and S positions on the pressure switch? It states starter relay and ignition switch. Where do I run these from? Can I just run wire from the starter solenoid? I am electrically challenged so if someone could be very specific I would really appreciate it. Thank you...

 

[Fireman431]

Re: Electric fuel pump wiring with safety pressure switch

I assume by wiring the electric fuel pump to the oil pressure safety switch you're thinking that the pump will shut off in the even the engine is not running? This also meand that the pump will not run until the engine is not running...or please correct me if I'm misreading your intentions. Most marine application frown on the electric fuel pump unless it is part of a high pressure closed loop fuel injection system. A standard carbureted engine does not need an electric fuel pump.

The light blue wire is usually wired to an idiot light, which will light up in the even of oil pressure loss.

 

[NYBo]

Re: Electric fuel pump wiring with safety pressure switch

Fireman raises a good point about the fuel pump not running when you are trying to start the motor. I believe there is usually a wire from the starter solenoid to the fuel pump, but I'm not sure of the specifics (coffee hasn't kicked in yet:redface.

 

[Don S]

Re: Electric fuel pump wiring with safety pressure switch

First, why go to electric at all? The Mechanical pumps are a lot more dependable, and doesn't take all the wiring. (Less problems)
Second, the light blue wire is for your gauge sending unit, which is not the same as an oil pressure switch.

The safety switch has 3 prongs P, I,S

This safety switch is what you have to install in an oil passage, usually Tee'd off the gauge sending unit. If your sending unit is by the distributor, you can use the oil pressure safety switch off the oil passage above the oil filter boss on the block.

Without actually seeing the switch or the instructions, I would guess that the I terminal on the pressure switch gets power from the purple ignition wire. The S terminal gets power from the Yellow/red wire from your starter slave solenoid going to your starter solenoid.

 

[drem312]

Re: Electric fuel pump wiring with safety pressure switch

I added one b/c the engine came to me that way I guess I could of drilled it out but i went with the carter marine fuel pump and there switch It runs for me flawlessly... heres a few pics of what I did to T it off one wire to the starter one to the pump and one to the 12volts key on I went from a 12 volt key on source off the purple, so on yours run a wire from the P on the switch to the new fuel pump positive side , ground the - wire from pump to block I used the same mounting bolt as pump,new wire from starter to the S on switch( on your starter the wire ,cranking wire, that has juice when the key is in the cranking position,starting,) and then I igition meaning a wire that has a full 12 volts when you put the key on this power is needed after the motor starts and oil pressure has been reached and the light blue goes back on the top original oil pressure ( the bell looking thing)

 

[jdogonhood]

Re: Electric fuel pump wiring with safety pressure switch

Thank you everyone. I appreciate all responses and took all into consideration.

 

[jdogonhood]

Re: Electric fuel pump wiring with safety pressure switch

Thank you everyone. I appreciate all responses and took all into consideration and figured it out. Thank you again. I love this site and forum and all the individual personalities.