Low readings on fuel and oil pressure guage

[eng622]

My fuel guage reads 3/4 full when the tank is full and the oil pressure guage reads below zero when the ignition is turned on and lowish when the engine is running. Are these guages supplied by a voltage regulator and is an earthing fault the likley cause. The oil guage sometimes takes a dip when the cooling fans cut in. The voltmeter and water temp guages seem to read ok however.

[daveb500]

An earth issue seems unlikely as most (if not all) of the dials and dash functions run off the same earth. I'm not sure about a voltage regulator but I would have thought it would need one so that's certainly possible.

edited:
Actually, I'm not sure that's true because some of the gauges are probably earth controlled rather than +ve controlled so ignore me.

Edited by daveb500 on Thursday 15th October 21:10