My fuel gauge is pegged ot past full. When my gas is pretty low in the tank the gauge starts to bounce around. Both tanks do this. Is it the gauge its self or the float in the tank. Can this be fixed if I do just a gauge cluster swap I was wanting a tach installed anyways.

Brett

 

It is the sending units. I have the same problem with both my tanks. The front tank on my 88 went first and about a year later the rear started doing it. The replacements are around $150 each. Too bad you have to buy the sending unit, float and pump come as a complete unit, from all I have found.

 

Look for an open wire in gauge circuit sender should read 145 Ohms full and 22.5 ohms empty from 88 manual. since both gauges read same look for common lead from tank selector switch to gauge or gauge itself. if you can find a resistor tie it to ground and to the gauge lead yellow /white lead from gauge/tank selector switch and gauge should read proportionally to resistor size between the 22 to 145 range . Good luck.

 

Do both sending units share a common ground?

 

I believe so. Did both tanks start doing it at the same time? With mine on the front tank the gauge would be pegged past full. When you got the about an 1/8 tank the gauge would bounce around till the bottom of the tank and it would read empty. The rear tank was fine. I picked up a sending unit (with pump, sending unit and float) and fixed the front, but the rear went some time after. If both tanks started at the same time it may be a bad connection.

 

My 89 did this as well.

I'd drive until the needle bounced, switch to the rear tank, and when that needle bounced I had about 5 gal of gas to find a station. Never fixed it as I don't need to know how much is there, just when I need more...

Did I mention dual tanks are great?

 

In the 88 manual the black lead for both tanks is tied together then goes to a gray connector with 12 terminals on the left hand side of the engine compartment, then to a splice and finally the ground point - unless you're having major electrical problems it probably under the body. The splice at the tanks is close to the tank sender for one of the tanks probably the front. Follow the rear harness to the front tank area and see if you can locate. Good luck.