No power to the fuel pump

Hi,

First, I attached the wiring schematic below for the powertrain management circuits. I highlighted things related to the fuel pump.

You mentioned the fuse was good for the EFI. In addition to checking the fuse, did you also check for power to and from it? Here is a link showing how it's done:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Next, when the ignition key is in the run or start position, power is sent to the coil open relay under the dash on left side. The power is supplied via a black wire with a white tracer. When power is applied, the contact which sends power to the fuel pump actuates and sends power via a black wire with a red tracer to the pump.

What I need you to do is this. First, go to the coil open relay. Turn the key to run and check power to the black/white wire. If it is there, check the black/red wire out for power.

If you haven't checked the relay, switch it with one having the same part number to see if it changes things. Or here is a link that explains how to test a relay:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

If there is power at the black/red wire and you don't get it at the pump, you must have a broken wire at some point.

Let me know what you find or if you have other questions.

Take care,

Joe

See pics below. Note: the schematics had to be cut in half to make them readable for you. I did overlap them so you can follow from one to the next.

Hi,

First, you are very welcome. Let me know what you find. Hang in there. We'll get it figured out one way or another.

Take care,

Joe

The green/red wire to the PCM is needed. The PCM provides a chassis ground via that wire. If that is disconnected, the CO relay cannot be actuated to power the fuel pump. In other words, no power is being sent to the pump simply because there is no power to actuate the relay.

And yes, if there is power to the green/red wire, then the black/white wire from the ignition switch is working.

I believe we found the problem.

Why is that wire disconnected at the PCM?

Let me know it that takes care of the problem.

Take care,

Joe

See pic below. It is from the manufacturer's schematics. I highlighted the indicator for chassis ground. That is the green/red wire even though it isn't indicated.

If you remove the CO relay is power present to it?

Also, pic 1 shows EA1 and EB1 connector locations.

Let me know what you find.

Joe

Hi,

It sounds like the ECM isn't providing a ground path. If it doesn't, the relay won't actuate. Take a look at my generic pic below. The + from the ignition switch to the relay must complete the circuit to the ground from the ECM. If that doesn't happen, the relay remains open.

The ECM (according to the schematic) should provide a chassis ground. You mentioned having the ECM disconnected to confirm power to the green/red wire and you have it. However, did you check for ground at the ECM on that pin?

Just as a check, ground the green wire at the ECM and see if the pump turns on. The ECM controls the pump by grounding. It's a theory at this point, but based on what you told me, that seems like the issue. If that is the problem, either the ECM has lost ground or the ECM is bad.

Let me know what I can do to help.

Take care,

Joe

See pic below.