Fuel Pump Question :S

[Brayden]

i just fitted one of the pumps from ebay, works a treat. i also went to the trouble of wiring in a relay so if the motor stops so does the fuel pump.

Where did you wire the relay to make it stop when the motor dies? I didn't think that was possible without an interceptor on the coil (or CAS).

[lambo74]

i tapped the wire from the oil pressure switch, so the way i wired in the relay was:
30- i ran power from the ignition
87- i wired to the fuel pump
86- i wired to the ground
85- i wired to the oil pressure switch

[Brayden]

Very clever! The only problem I can see will be starting the car when it hasn't been going for a while, because the fuel pump won't go while the engine is cranking. (Low oil pressure.)

[lambo74]

yeah true, so what i did there was i also wired the fuel pump to a push button switch so i can prime the carby if i leave the MB sitting for a while.

[Brayden]

Nice work! You've thought of everything.

[jeff]

Howdy , lambo which ignition wire did you use for power, im just about up to this in a rewire and agree some very nifty planning on your behalf, cheers

[lambo74]

Hi Jeff, i used the black wire with white stripe.

[Brayden]

Which from memory is the one that triggers the carby shutoff solenoid, correct? If not then it would be a suitable alternative.

[mowog]

just thinking out loud here so feel free to pick, (as if you need my permission!) but if you run an additional wire to the fuel pump from the small activation wire to the starter solenoid it will only carry current when cranking and will provide power to the fuel pump while cranking. no relays or whatever required. true??

[Brayden]

Sounds plausible to me!

[jeff]

Im not the best with auto electrics but I think you would need a diode to prevent cross- energising the circuits ( I say this only because I had to make up a Diode pack for the idle up on the G10 ) but it does sound feasible cheers