Another fuel pump question

[paulhagedorn]

This is for a '73 2.0 fi. My guess would be yes, but is the fuel pump supposed to run when the car is cranked? The PO moved the fuel pump up to the fron of the car when he switched to carbs and ran his own hot wire to the fuel pump. When I try to start my car, the fuel pump cuts off and pressure drops to about 5 psi.

Where can I tap in to get a wire that is hot when the key is on and cranked?

Thanks,
Paul

[Dave at Pelican Parts]

The fuel pump is supposed to be controlled by the ECU. It will go on for about a second when you turn the key from "off" to "on" (the position before "start"). It will go on while the starter motor is cranking. It will stay on when the engine is running, but will turn off when engine RPM drops below about 100. That's to avoid dumping fuel in the event of an accident.

The best place to get power for the pump is from the pump relay, same as is done when the pump is in the back. That means running another wire through the center tunnel. It's not *that* hard.

I have used a coat hanger and electrical tape to run extra wires in my car. I have found it easiest to pull the rubber boot off the bottom of the firewall and push the coat hanger up through it. Then tape the wire to the hanger, and pull down. Then push the hanger forward through the hole (mine has to make a bend to the left and then back to the right) into the center tunnel. It can take some fishing through that square access panel in the top of the back of the tunnel to grab the wire. Remove the tape and pull the wire along the main wiring harness, up to the front of the cockpit. I don't know exactly where the wires go forward into the trunk, so you'll have to figure this one out. (And let me know, please.) Then run the wire down to the area of the fuel pump.

Or, if you like extra holes in the car, you can drill and run the wires anywhere you want. (Not an idea I like much.)

Anyway, splice the new wire into the old fuel pump power wire (black with red stripe, at least on some cars). You can ground the pump on any solid grounding point.

If you don't want to do all of that work, then connect the pump to the fuse panel. One of the fuses for "switched power" (#8 or #9 I think) has an extra lug on it. But this will place an extra load on the switch. If the switch is marginal, it might fail from the extra load.

Good luck!

--DD

[paulhagedorn]

Dave,

Thanks for the advice. I did finally find where the orignial wire was for the fuel pump. I took your suggestion with the coat hanger, but tied the wire to it instead of taping it. It worked great! I did not get the opportunity to route the wire through the front trunk because the PO took the liberty of drilling a hole when he rewired the fuel pump.

I did find a place that looks like it would work well for routing the wire through the front trunk. Behind the radio there is a hole(at least, on my car) that I think is for the antenna. It comes out right behind the gas cap. If you open your trunk and look behind the fuel tank on the left side, you should be able to see the hole. You could then take the wire around the left side of the tank and down.

If I can find a way of getting it to around the tire without having to drill holes I will post again.
Found two places that you can get the wire. The first, which requires the least amount of wire would be to make the wire follow the pressure line coming from the spare tire. Of course, you would have to remove the gas tank to do that. The other one would be to take the wire towards the driver's side and then follow the existing wiring harness through the wall on the driver's side. This one is probably the easiest because the tank doesn't have to be removed(i don't think!).

Where exactly are you trying to go for the fuel pump?

Mine is right below the tank where the steering rack is.

Thanks for the helpful hints,
Paul

[This message has been edited by paulhagedorn (edited 07-26-1999).]