Oil Pressure & Fuel Level Gauges Not Working

[pgilling]

Hi, can anyone offer advice? The other gauges are working fine but the needles are dead on both the fuel level and oil pressure gauges although the low oil pressure warning light works. I've checked the connection on the oil pressure sender which seems ok, but not sure where to start with the fuel gauge. Before I start pulling everything apart I was just wondering if anyone knows if these faults are linked? BTW, I've just received this car from the States and not really driven it so I don't know it's history. It's a 1977 Californian model.

[kilrwail]

It's too early for me to go pulling wiring diagrams, but since two gauges have failed simultaneously, I'd look at the grounds at the gauges first. Do the lights in the gauges work? If not, that's another signal that it may be a grounding issue. Very often with these cars the grounds need to be cleaned and tightened to fix electrical issues. Good luck!

[pgilling]

Thanks kilrwail, yes the lights to the gauges are working so I'll have a look at the wiring diagram. I guess I was after a quick fix by hoping someone would have experience of this problem.

[seabeelt]

You can check the fuel gauge by grounding one at a time the two wires attached to the sending unit in the trunk. One will make the red fuel light come on, and the other should peg the gauge as full. If both of these indications work, then the sending unit needs to be replaced. Do a continuity check from the oil sending unit with the wire unplugged from the unit to the back of the gauge. If wire reads ok, then that sending unit needs to be replaced. Both sending units are grounded already. Fuel via the tank to the frame and oil to the engine and then to frame.

[pgilling]

Hi seabeelt, thanks for your help and advice but it seems I was missing the obvious as the fault was caused by a poor connection on the fuel tank. The car is new to me and because I'd had the instruments out I assumed I'd disturbed something. I looked at the wiring diagram and there is a common link with the oil pressure gauge and the fuel level, so there we go, another lesson learned!

[seabeelt]

Glad you figured it out