2.3L ('83-'97) Fuel Pump issue

[DandysRanger]

Got stranded in the Ranger the other day. It just died at a stoplight and would not restart. I had it towed home and when I turn the key, I didn't hear the fuel pumps turn on. I assumed the relay had gone bad (again) and purchased a new one. When I replaced it, the truck ran again for a few minutes before dying. I tried the test port and I can hear the frame mounted pump turn on but not the in-tank pump. So, am I looking at an ECM issue? I had it refurbished a couple of years ago by ECUExchange.

 

[alwaysFlOoReD]

Test your fuel pressure and volume. You have a carb? Or fuel injection? I'm not familiar with 85 2.3l.

 

[DandysRanger]

It's fuel injection. I need to test it, but I loaned out my fuel pressure test gauge. I think that not energizing with the key on might be the issue.

 

[DandysRanger]

Update: It will start and run with the fuel pump test port grounded. As soon as I remove the ground it runs for a few seconds and dies. I still don't hear the in-tank pump running.

 

[DandysRanger]

Still trying to diagnose this. I'm looking at a wiring schematic in my Hayes manual but it does not match what I'm seeing on the car. In the pic are two relays. The one on the left is the fuel pump relay and the one on the right is the EEC relay. Or are they switched?
The relay on the left has a red, yellow (hot), orange/blue and a brown/blue.
The relay on the right has a green, Black/yellow, and two reds.
Is there a better source for a schematic?

 

[Mechrick]

The ECM should be grounding the test port connector briefly when turning the key on (prime pulse). Check it with a test light clamped to battery positive or a meter.

After the prime pulse when the ECM reads a crank signal, it will also ground the relay circuit and test port to rum the pump(s).

 

[DandysRanger]

The ECM should be grounding the test port connector briefly when turning the key on (prime pulse). Check it with a test light clamped to battery positive or a meter.

After the prime pulse when the ECM reads a crank signal, it will also ground the relay circuit and test port to rum the pump(s).

I'm not sure I understand this. When I hook a test light between the test port and the battery + the fuel pump goes on without the key.

 

[Mechrick]

Your test light must be passing enough current to trip the relay.

Check with a volt meter, one lead on the test port and the other on battery positive.

 

[DandysRanger]

Your test light must be passing enough current to trip the relay.

Check with a volt meter, one lead on the test port and the other on battery positive.

Ok. Did that and nothing happens.

 

[Mechrick]

I think the next step is to check for that momentary ground right at the PCM. It's pin 22 tan/lt green. You can test it the same way, with one volt meter lead on batt positive, the other on pin 22 at the PCM, when turning the key on the pin should ground momentarily and the DVOM should briefly show 12 volts.

 

[DandysRanger]

Update: I hate it when posts are just left hanging with no solution.
Thanks to @Mechrick for suggesting checking the pins. When I pulled the harness plug off, two pins came out with it. I sent it to ECU Exchange and they were able to replace the connector for a quite reasonable $40 + shipping. Problem solved. This is the second time I've been bailed out by them when I was left just scratching my head.
I'm glad to have the farm truck back.