Hey folks,
I just inherited my dad's '71 914/4 1.7L, and I'm having a (typical?) litany of problems that I would love some advice about. I was able to transport the car from my aunt's house in Nashville to Southern Oregon where I live. It was "running fine" before I got it and was able to drive it from the auto transporter's dealership ~0.5 mile home, but when I tried to take it out for a jaunt later that afternoon, it idled out at the closest stop sign. Turns out my aunt hadn't put any gas in it in a year and the tank was bone dry. It was a miracle of God that I was able to get it home. I filled up the tank with ethanol-free premium and tried to get it to start, but the car would only turn over. Since then I've been interrogating every aspect of the car from the fuel lines to the electrical, and I've come to the following conclusions using my voltmeter and other tools:
1. The empty tank killed the recently-installed rebuilt fuel pump
2. The relays and relay board are in good condition after a thorough cleaning of the connections and fuses. There are no broken connections.
3. There wires to the fuel pump are intact.
3. The Power Relay turns on when I turn the key to "On", but the Fuel Pump relay does not click on. I've narrowed this down to there being a faulty ground at the Fuel Pump relay (i.e. point 85), as I have voltage on both point 86 and 30. Point 85 connects to the III connector which in turn connects to the Control Unit. These wires are intact.

So my question is: Is it likely that a faulty ground in the Control Unit is causing the Fuel Pump relay not to activate, or am I missing something? I've traced all the wires in the wiring diagrams and it seems to me that the Control Unit has it's own ground, but I'm not sure how to check that. Has anyone else seen this problem before?

Also, it seems odd/conspicuous that I would have a fuel pump failure AND some new electrical issue with the fuel pump relay at the same time.

I'm a novice to the car so even basic advice is welcomed.

Tom

Have you remotely tested the fuel pump ? Outside the D-Jet system, with battery or remote 12 volt supply ?
Is it still under the engine tray ?
D-Jet system grounds are under intake plenum.
Relays are pretty quirky. Maybe pull out the fuel pump relay and widen out the pins with a razor blade.

Please be aware that the wiring harness may contain high high joints. The wire has become brittle under the plastic sheath. The heat of the engine allows the sheath to "flow" and allow the broken internal wire to touch and complete the circuit. When it cools the circuit will go open. This may be a cause of your problem.

Ooof, troubleshooting electrical over the Internet...

Start simple: jumper the connections under the fuel pump relay and see if the pump runs continuously. This (hopefully) eliminates concerns with the fuel pump circuit.

I presume you've tried another relay?

Note that the fuel pump relay solenoid is grounded by the D-Jet computer under three conditions: one, an initial ~2 seconds when the key is turn ignition on; two, when the key is in the Start position; three, when the ECU detects ignition activity.

Greg