No power to fuel pump, seems to be a common problem around here Options

[warrenoliver]

Car stalled on me this morning. When I tried to restart, the fuel pump would not turn on so no luck with the start. Towed it home and checked it out. It is a 73 2.0 with FI.

The pump runs when I jumper directly to the battery. I have continuity from pump connector to the #13 pin on the relay board. If I jumper from the fuse to the #13 pin, the pump comes on. The fuse is good.

I have replaced the main power relay and the fuel pump relay with known good ones. With the ignition on, when I remove and reseat the main power relay, I can feel the relay click but I do not hear the injectors click nor do I hear the fuel pump start (I got this test from Dr. 914's Tech Tips).

On the fuel pump relay socket, I have power at the 30 pin and also the 85 pin. When I jumper to the 87, it does not turn on the fuel pump.

I don't know if it is related, but I have the same problem with the heater blower relay also. I jumpered 30 to 87 and I do not have power. I am not sure but I think the car died when I had the heater blower running.

I'm stumped. What do I check next?

[Tom]

Warren,
From what you have said, it doesn't sound like an ECU problem.
Also powered at the same time as the fuel pump is the AAR, which has a noted problem of shorting and draining power. Try disconnecting it and see if things work better. You can by-pass the ECU function by providing a ground to the fuel pump relay by jumpering a ground to pin #3 of the 4 pin connector that goes to the ECU. This will energize the fuel pump relay anytime the key switch is on.
If all else fails, you can run your auto-x tomorrow by jumpering the fuel pump relay, jumper fuse 13, the rear most fuse, to the pin #13 of the 14 pin connector. Just remember that the fuel pump will continue to run anytime the key switch is on, even if the engine has stopped.
Tom

[warrenoliver]

Tom,

I unplugged the AAR and it didn't help.

I have found a discrepancy in the relay board diagrams and now I am unsure exactly which pin/socket i am supposed to have power to at the fuel pump relay with the key on. All of the descriptions say 86 should should have 12V on the fuel pump relay - mine doesn't. Brad Ander's diagram shows 85 and 86 pins swapped on the relays. I made a new post asking about that.