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,
Sorry to not answer back sooner. I have been dealing with the loss of my 16 year old puppy. It is hard when a pet you have had for so long passes.
For some reason you are not getting current flow thru the pin 30 connection on the fuel pump relay socket. It could be corrosion in the socket or corrosion where the #30 pin connects to the traces on the relay board.
Most folks assume that if there is 12 volts there when they test, then the equipment should work. Voltage is potential, current is power. Dirty or corroded connections may give a voltage reading, however when current is needed to run the equipment, the connection will not supply the necessary current. You can think of it like this: a 1/4 inch hose will give a reading of 50 PSI, so will a 5 inch hose. The 5 inch hose will flow a heck of a lot more water than a 1/4 inch. Think of the 5 inch hose as a good clean connection and the 1/4 inch as a dirty/corroded one. They both may give you a voltmeter reading of 12 volts, only one will give the current necessary to power the equipment.
Here is what I would check given your tests and results; check the sockets and relay prongs of the power relay and the fuel pump relay to make sure they are clean and make tight connections. You can spread the relay prongs slightly with a small knife to try to ensure they make good tight connections with the relay sockets. The sockets can be cleaned with a small bit of sandpaper rolled up to fit in the socket, or a small wire brush will clean the sockets also. It sounds if your relays are working, so concentrate on the prongs and sockets to see if you can get good connections.
Hope this helps,
Tom

[warrenoliver]

Tom,

I think you may be right but I just don't know. I am hesitant to tear into the ECU and make more problems. I have already spread the prongs slightly and have tried to clean the sockets but I will try to do some more to see if I can make some sense of it.

Thanks.