Quote:
Originally Posted by Quikshft
Wish my new L31 had provision for the mechanical fuel pump but alas - no.
I'm going to run the Holley Might Mite, and already have a relay and oil pressure safety switch like depicted in the diagram. I believe I can run the wires as the diagram shows, but as an electrically challenged individual I am not certain what is happening at the safety switch. I think the desire is for the fuel pump to run while the engine is cranking? So the wire from the "S" terminal on the starter solenoid will provide that correct? Then when the engine starts, the pressure switch closes and the solenoid quits feeding but a "Key hot" from the ignition switch takes over? Does that "Key hot" really need to come from the ignition switch or can I find something on the fuse block near the clutch/brake pedals under the dash?
For my own peace of mind let me know if I've got this right. Thanks!
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Looking at the diagram I see that the N and C are connected but no power goes to them until the S terminal (starter solenoid) is energized. This closes the FP relay and the pump runs until the starter is de-energized. Then the oil pressure switch is closed from the ignition switch through NO to C which keeps the FP relay energized until the key is shut off or the oil pressure drops and re opens the connection between the NO and C connection.
The only thing missing is how the FP relay is closed when just the key is turned on initially. I believe there is a separate circuit which is the fuel pump prime circuit not shown on the diagram above which has a separate relay circuit. I seem to remember reading about something like that in the manual.
Some of our newer vehicle mechanics may be able to better explain how that works if they chime in.