Fuel Pump issues on a 91 740 with Regina System

[TommyB]

Have a 91 740 4-cyl without turbo and 176K miles. Had a dead fuel pump sometime last year and replaced it. I have the Regina System which only has one pump that is in the tank.

I am now experiencing the fuel pump "coming and going." I thought that I had another defective pump and replaced it with yet another new one under warranty. BUT, I am still having this "sometimes current to the pump and sometimes not." I have replaced the relay and still have the problem. When I put the second new pump in the car I did replace the wiring on the system that is within the tank. No problem there.

Is there any type of control unit between the key switch and the pump that could be defective and not allowing current to the pump? I ask as a neighbor said it could be my switch itself. But I don't think so. Anyone ever heard of this issue?

Help!

TommyB

[billofdurham]

I have checked the wiring diagrams for the Regina and the other 740s and the pump would appear to feed straight from fuse #11, not the relay.

I would suggest that you take a wire direct to the pink wire on the pump and see what happens when you miss out the switch. Also check that the earth (ground) at the pump is good as this could also cause intermittent breaks in the feed. You could try running another wire from the earth to a different point.

Bill.

[jonesg]

I did my regina pump last week, replaced the in tank wiring same as yourself, I was told the position sensor on top of the flywheel plays a part , if the ECU doesn't see the engine turning it shuts the fuel pump down. So I changed that too, not that there was a problem but the rubber casing was peeling away from the wire anyway so...
Its just another sensor that affects the pump and they tend to go intermittent causing hot start problems.

In the rear wiring compartment (mines a wagon) I stripped a bit of insulation back from the pump leads and clipped a multimeter into the circuit so I could watch what happens during cranking etc. It didn't reveal any problems so I guessed correctly the pump was dying.
The gas guage is in that same same harness , if theres a problem in the harness it'll show up on the guage too..maybe.

Was the original pump you pulled out bad?
mime was toasted, one brush was gonzo.
The plastic around the area where the wire is soldered to the pump was burnt.
If your pump looked ok the problem was/is elsewhere methinks.

[diego940gl]

I have a 1992 940 gl regina and no power to fuel pump! New relay, but no power to it.