So my 1990 740 Turbo how to pre frequent problem where I won't show me how much gas I have in the tank. There will be times while I'm driving that it'll kick on and show me how much gas I have, but usually it just says I'm totally empty. My Turbo abd speedometer, but not my gas. Anybody have an idea as to what could be the problem?

 

the gas gauge in the dash is connected directly to the fuel level sending unit in the gas tank... there's an access plate on the floor of the trunk just behind the back seat, and on the left side, the wiring and hoses go through this plate.

if that wire, or the ground wire, are intermittent, that would account for the gauge being intermittent.

 

Intermittent issues are the worst. In this case it could be the sender in the tank, the gauge in the instrument panel, or the wiring in between. Not much help with this--unfortunately you have to test these when the fault is happening. If it happens only rarely just wait til it goes out completely, then it's easier.