What could cause the fuel gauge to stay pegged on full in an Oldsmobile Silhouette?

Answer 1

I have a 97 olds silhoutte with the same problem. My mechanic said they have to drain the fuel tank, replace what ever detects the gasoline, and put it back together. You are looking at some hefty dollars. I've chosen not to do it but to just change my trip meter everytime I get gas. Whether my mechanic was pulling my leg or not...it said it could cost upwards to a 1000.00 to do the job. Knowing I get about 16 to 18 miles to the gal locally and upwards to about 24 to 26 on the highway....I don't have a problem watching the trip odometer.

Just to add. We did the same thing with our trip odometer until the fuel pump gave out. The gauge and pump are all part of the same assembly and can't replaced seperately. It cost around $600 when our mechanic did the work. The scary part about the gauge is, we got used to the odometer thing and thought we would do it for ever, until the van decided to die in a parking lot. It wasn't any fun getting out of work to go coordinate getting a tow truck to come pick the van up.

I have the same problem with my 1997 Silohoutte and my mechanic told me that it would need fuel sending unit.. spend big bucks!!

The fuel gauge doesn't have to be replaced when you replace the sending unit/ fuel pump--your mechanic snowed you. If it pegs to the right all the time--then it's your gauge, if it does whatever it wants when it wants it is your sending unit/ fuel pump.

Just to add....both of you or all of you could be correct. The fuel level sender is an electronic switch with an arm attached on the side of the fuel pump. It is usually integrally molded with the pump, however in this case, it can be replaced seperately. The downside to this is you do have to remove the fuel tank and then the fuel pump is likely to go out shortly after replacing it. GM is known for having a poor pigtail design on these senders, causing a short. This will cause the gauge to read full all the time. You can try to lower the tank, then replace the fuel pump pigtail(both female and male ends), or attempt to repair the wires on the top of the tank. The old style design caused the wires to rub on top of the tank, thus causing it to ground to the tank and short circuit the gauge. If I were to drop the tank on the van and it had more than 80k miles, I would replace the fuel pump module(assembly) though because GM is not known for having the most reliable pumps.