Pump stayed running

[Creomod]

I pulled in garage and turned car off . And I heard a sound. It was the pump. Stayed running for about a minute after I pulled key out. Went for a drive right now. Car shut off. Looked at fuel gauge key forward and it didn’t move. Waited a few minutes. Did it again. This time gauge did go up it started drove home . Think it’s the fuel pump

 

[AeroCoupe]

Pull codes before you do anything. Could be the ECU needs to be rebuilt or it could be as simple as the fuel pump relay is bad.

 

[Creomod]

Pull codes before you do anything. Could be the ECU needs to be rebuilt or it could be as simple as the fuel pump relay is bad.

Pull codes before you do anything. Could be the ECU needs to be rebuilt or it could be as simple as the fuel pump relay is bad.

Bad ecu even with no key in ignition?

 

[AeroCoupe]

Yeah missed that. Ignition switch issue?

 

[Creomod]

Yeah missed that. Ignition switch issue?

Hmmm didnt think about that. The ecu was rebuilt like 3 years back so I don’t think that was it either way. O god I didn’t run codes and ordered a pump. Gets here Saturday. I know it’s not the relay cuz I always carry an extra one with me and when it shut off I swapped it and it still didn’t make a difference. Well I’ll replace the pump and if it still does that I’ll run codes and look at the switch. Thats also replaced recently like this past year. The pump was also replaced recently under a year ago it’s a walbro 155.

 

[AeroCoupe]

I’d lean towards the switch. How would the pump run with the switch off? It doesn’t make its own power.

 

[Mcmahst]

But, if the relay trigger coil loses power BUT, the contacts stick or etc, the pump will not shutoff (FPR is always hot). But, the pump is activated by the ECU grounding it, so, the pump would seem to be the least likely culprit. More likely a bad ignition switch or whatever feeds those systems.

 

[Creomod]

But, if the relay trigger coil loses power BUT, the contacts stick or etc, the pump will not shutoff (FPR is always hot). But, the pump is activated by the ECU grounding it, so, the pump would seem to be the least likely culprit. More likely a bad ignition switch or whatever feeds those systems.

When you say whatever feeds those systems what feeds those systems?

 

[LILCBRA]

I think he means if you have some other type of switch to control power through the car. Some people use toggles, for example, to control power to specific systems.

 

[Mcmahst]

I was trying to say ^^^^ that, but also postulating, what could cause the pump to continue to run after the car was “turned off.” It would have to be linked to the ignition switch, because if it’s functioning correctly, there’s no method for the pump to run. And, at the same time, you would likely have a malfunctioning ECU. So, if not the ignition switch, there’s no method must be some weird wiring problem to make this possible.

 

[AeroCoupe]

The fuel pump relay gets power from a fusible link at the starter solenoid. The power for the coil on the relay comes from the EEC power relay. The ECU sends a ground to the fuel pump relay which then closes the contact across the relay and sends power from the fusible link to the fuel pump. So with the key off there is no power from the EEC power relay to the fuel pump relay and there is no power to the ECU so it cannot send a ground to the fuel pump relay if everything is working as Ford intended.

- The fuel pump relay contacts could be fused and thus putting power to the fuel pump but then it would run constantly.
- The EEC power relay contacts could be fused and putting power to the coil side of the relay but it would need a ground on the other side of the coil to energize the pump so there would also have to be a failure there to make this scenario work.

Have you looked at the wiring on the ignition switch? Remove the connector to the ignition switch and see if the switch seems loose or separates into two pieces or just comes apart partially. These switches fail so really look it over.

 

[manicmechanic007]

The processor is what's faulty and it's keeping the fuel pump relay energized
Replace the caps in the processor and see if the problem is fixed

 

[Noobz347]

The processor is what's faulty and it's keeping the fuel pump relay energized
Replace the caps in the processor and see if the problem is fixed

The ecu was rebuilt like 3 years back so I don’t think that was it either way.

Bad ecu even with no key in ignition?

I'm not so certain that the ECU is the issue either. Something else appears amiss

My brain is scratching at the idea of either stray voltage. I also considered an intermittent ground but that makes no sense with the ignition off. So, I'm back to a stray voltage theory. Is it possible to get a reading between the pump feed line and ground when this occurs? That pump will rotate at even 6 volts.

 

[manicmechanic007]

It's the classic symptom
Just because the processor was rebuilt does not mean it is any good
Test it
Backprobe the fuel pump relay and see if the processor is keeping the ground provided to the relay

 

[Noobz347]

To be clear: The EEC was rebuilt. The "processor" is a component inside of the EEC and was probably never touched. They are not known for failure.

A rebuilt EEC is not 100% but that tidbit combined with the EEC pulling voltage [past] the ignition switch in [OFF] position suggests that it might be something else.

Should be easy to check: Pull the ECU and see if it still does it.

If not then: https://www.theecuexchange.com/

 

[2000xp8]

I used to have a relay that I had to knock because the pump stayed on. Key on or off? I don't remember. On a 1990 it's under the drivers seat so it was easy. I would just reach under and knock it on something.