gas gauge reads PAST full

30

Asked by Jun 03, 2011 at 12:07 AM about the 1993 Oldsmobile Cutlass Supreme 4 Dr S Sedan

Question type: Maintenance & Repair

ok, my gauge reads past full, i took it to a shop to diagnose it, the guy got into my trunk and played with some wires, and then told me that it is the gauge itself, well, as you cant buy single gauges for this type of setup, i went and got another head unit, well when i hooked it up, turned the key, the gauge went right past full, so im thinking its not the gauge itself, so i dont know where i should be looking for the problem, i would rather NOT drop my tank and see, i did disconnect a wire that was sitting on top of the tank,  no diffrience in the gauge, so im at a loss to tell, it did go to empty only once when i ran out of gas, but went right past full when i turned the key back on, on or off the thing reads past full

7 Answers

435

sounds like the float in the tank is stuck. it most likely needs to be replace. dropping the fuel tank is easier than it seems. a few clamps and some bolts for the straps holding the tank.

1 out of 1 people think this is helpful.
30

yeah, its just jacking it up and doing it, i know how to, just dont look forward to doing it, and im trying to find a way to test to make sure its the sending unit, i just think it maybe a bad wire someplace, it reads way past the full line...so it doesnt seem to be a stuck sending unit

30

anyone have any idea's how to test this? there are 4 wires going into the tank, i need to know wich one's wich, there's a purple wire, two black one's and a grey or white one

3 out of 3 people think this is helpful.
10

why dont you just test the wires to see if there is voltage going to them from the wire to the chasis, or you could also do a ohm test, just make sure the car is off when you do that

1 out of 1 people think this is helpful.

i have the same problem but i think my problem is the cluster

My car is doing the same thing I need some answers to

3,385

Hello, Here is a good explanation for "Full"...remember, if reads empty, sender wire is fully grounded ( also wire pinched to ground), and "Full" should be a measured higher resistance as the Tank float rises up... Past full, in summary is open wire...anywhere from the gauge to the harness at the tank. Hope this Helps..ATM ***********************If your gauge reads FULL AT ALL TIMES: A. Probable Causes Wire from dash gauge to sending unit is broken and/or the connection is corroded (not making a good electrical connection). Resistance wire inside sending unit is broken Sending unit is not properly grounded to tank or tank is not properly grounded to chassis B. Testing Remove the wire from the contact stud on the sending unit and ground it to the chassis. If the gauge now reads Empty, the trouble is either poor grounding of the sender or a bad sending unit. If the gauge still reads Full, touch a grounded test wire to the sending unit terminal on the back of the dash gauge. This terminal is often marked with a red tag. If the gauge now reads Empty, the wire from the dash to the sending unit is broken or the connection to the dash gauge is corroded. With the sender removed from the tank, connect an ohm meter to the sending unit (one lead to the contact stud and one to the housing) and check the resistance of the sender as you manually raise and lower the arm. This reading should be 0 to 30 ohms (or very close). If none of these tests finds the problem, the dash gauge is the problem and should be rebuilt or replaced. C. Repairs Make sure that a good ground is present at the dash gauge and also at the sending unit. Run a separate ground wire to the chassis if necessary. Sliding contact arm may not make good contact to the resistance wire windings in sender. If you are experienced with electrical repairs you may be able to clean the wiper and resistance wire coil or replace the wire. Otherwise send the unit to a specialist or replace the unit. Check for good ground at sender body and gas tank.

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