Fuel pump not running despite good pump, relay, and electrical. Any ideas?

[ETurdy]

I confirmed that we do not have an OBC system (side note, we have an analog clock).

I connected pin 85 of the relay directly the ground (at the strut tower). Doing that allowed the relay to switch when I turned the key to the run position. This seems to confirm that there is a bad connection somewhere between pin 85, the DME, and ground. Are there any likely suspects for this?

[e30sh]

Someone added that clock. I'm not aware of any US cars that came with the analog clock. Even the 84-85 318 here got the digital clock. It most likely still has the OBC harness in it. If it has a power sunroof, it's an iS.

The ETM shows some ground point routes. Check those. Since someone added the clock, look for "stupid" wiring mods.

[ETurdy]

I believe you are correct that someone added the clock.

When I pulled the dash panels off, the first thing I looked for was poorly done wiring, but nothing looks out of place.

I checked for the OBC relay box in the location shown in figure 5 of page 7000-5 (https://drive.google.com/open?id=0B4...FBScTRnblFSUEU), and there is nothing there.

I'm not sure what else to check with regards to the OBC system. I understand that the car was most likely originally equipped with it, but I can't find any signs of it. I'm guessing whoever swapped the clock in also fully deleted the OBC harness and relay box.

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So, if that's not what's stopping the fuel pump from turning on, what is? I have confirmed that directly grounding pin 85 on the fuel pump relay (as shown in this image https://drive.google.com/open?id=0B4...nM4UFFSNjNUdHM) will send power to the pump when I turn the key to 'RUN'. That confirms that the main relay is functioning properly, sending power to pin 86 on the FPR.

Without the added ground, and with the FPR unplugged, I measure >12V between pins 85 and 86 with the key turned to 'RUN'. Does this imply that the DME is grounding the relay, and there just isn't a good connection? Or, would it be possible to read 12V across these pins even without a ground at 85? I thought the DME was only supposed to ground the fuel relay only when the CPS indicated that the engine was rotating, but when I measured 12V across the coil, I thought maybe that was wrong. Any experts on how the DME triggers the fuel relay, please chime in!

Thanks again for all the help!

[e30sh]

See page 1360-5 The FPR coil ground path pin 85 says fuel pump relay control in the Motronic case. Maybe it's as simple as a Dme issue since your fine up to pin 86 12v side.

What ohms do you get if you probe pin 85 socket to ground, with and without key in run?

[ETurdy]

Well, it looks like the issue isn't even an electrical one. The first time we measured the fuel pump voltage while cranking the engine must have been a false negative, because when I just checked, we get power at the pump.

We popped the pump out to check it, and it looks like that's our problem. With 12V across it, it makes a little click but then doesn't do much of anything else. I wasn't sure how loud it should be, so I initially hadn't thought much of it.

We got a new pump today and it is obvious that it runs when cranking the engine.

Thanks for all the help! If nothing else, I at least have a better understanding of the OBC and fuel pump electrical...

[T0x1x]

Thanks for the help everyone, she's up and running! AND we know way more about OBC specifics!