Electric fuel pump wiring
Drifting
Joined: Nov 2001
Posts: 1,469
Likes: 6
From: 68 427 4.11s Roadster
Well I don't know if its the best but I hooked up to the "aux" on the fuse box. Partly because theres a switch under the dash.
The wire still has to travel to an oil pressure switch and your starter crank circuit, or at least its spoda. I did away with the starter hook up and just prime it manually.
The wire still has to travel to an oil pressure switch and your starter crank circuit, or at least its spoda. I did away with the starter hook up and just prime it manually.
Melting Slicks
Joined: Sep 2004
Posts: 2,655
Likes: 19
The pumps can pull some current, so splising into an existing keyed ignition wire may no be the best idea.
I've had good luck with the following.
Pump to iol pressure switch. Switch has one lead that goes to starter solenoid terminal (the one that has the bypass to the coil). This provides current to the pump while cranking and there's no oil pressure.
The other lead from the switch goes to a relay that's triggered by the ignition switch (run position, which supplies current when key is on and there's oil pressure) The relay is wired to a fuse.
I've actually skipped the relay and just wired the switch to a fuse directly.
Gary
I've had good luck with the following.
Pump to iol pressure switch. Switch has one lead that goes to starter solenoid terminal (the one that has the bypass to the coil). This provides current to the pump while cranking and there's no oil pressure.
The other lead from the switch goes to a relay that's triggered by the ignition switch (run position, which supplies current when key is on and there's oil pressure) The relay is wired to a fuse.
I've actually skipped the relay and just wired the switch to a fuse directly.
Gary
Pro
Joined: Jul 2002
Posts: 723
Likes: 0
From: North Port, FL
I would suggest a slight variation to Garys 68. The fuel pump oil pressure safety switches are only good for ~7.5 amps and they will soon burn up switching the full load of a pump (ask me how I know this). The safety switch has three terminals. the normally closed terminal should go to the "R" or the "s" terminal on the starter. The normally open terminal goes to a keyed ignition source. The common terminal goes to the activation coil of a 30A relay. The relay is the switch for the pump from a fused source. Of course the other side of the activation coil on the relay goes to ground.
In operation the safety switch directs a signal from the starter to activate the relay while cranking and before there is oil pressure. After there is oil pressure the safety switch directs a signal from the ignition source to activate the relay.
Another twist on this is to put a securety switch hidden under the dash that interupts the conection from the common terminal on the oil pressure safety switch to the relay activation coil.
I would show a wiring diagram but I cant get my scanner to work right now. I can provide one from work tomarrow if you are interested....Jim
In operation the safety switch directs a signal from the starter to activate the relay while cranking and before there is oil pressure. After there is oil pressure the safety switch directs a signal from the ignition source to activate the relay.
Another twist on this is to put a securety switch hidden under the dash that interupts the conection from the common terminal on the oil pressure safety switch to the relay activation coil.
I would show a wiring diagram but I cant get my scanner to work right now. I can provide one from work tomarrow if you are interested....Jim
