I have a 2002 C-5 conv. My ? is. When I fill the tank the fuel gauge registers full , but the heads up shows only 1/2 tank. I was told the octane or use of diff. kinds of fuel might effect the sending unit. Anybody's input would be appreciated.

Thank you, LMan

 

i have never heard that before,new one to me.i run all kinds of fuel different octane level fuels, leded., and unleded,the only thing i notice with strong gas,highe octane,,like race gas is it will eat the fuel lines up in time,, on a vette octane will not mess up a fuel sender,

 

I suggest: just live with it. C5s have strange gas guage reactions. I believe there is a factory recall/bulletin/fix -- a friernd with an '02 ZO6 had his dealer replace sending units, etc, under warranty, and said it "fixed things" - whatever things were.

My car acts very strange at times: 1) the gas guage is very non-linear---I fill it up, drive 80 miles and it still registers full, then drops to half a tank in the next 50 miles, 2) when I am at 1/4 tank indicated and go fill the tank, afterwards the guage registers only 1/2 and only slowly goes up to full within about 10 miles of driving, but the digital display below the tach and speedo says "On rserve fuel" or whatever the warning is, for several minutes after refilling.

I treat it as a quirk, just one more reason to love the car.

 

GM has a whole plethera of update reflashes on the PCM on all their vehicles. If I have time, I can check TSB's on that to see if there is a correction. Sometimes, they don't even post those corrections until you do the reflash and see what it corrects. You might check with your GM dealer about any updates available for your car, kinda like updateing your video drivers or sound card drivers on your computer. The instrument panel is controlled by the Body Control Module and there might be a body control code that you can only access with a scan tool. [8D]

 

Thanks for your responses.
I talked with a dealer and recieved the usual resonse. We need to run an evaluation. $85.00 Thank you. I also talked to A.C.I. The good news is- They just recieved a flash on this very problem. One solution is a fuel cleaner/enhancer called 4K made by a compay called BG. The info stated that some fuels cause sulfur build up on the sending units. The issue was delt with in two ways. Keep changing make of fuel; use the BG fuel cleaner. I guess I'll try both before a more expensive route. I'll up date the results.

LMan

 

It fixed itself. One of things. The fuel additive, Shell gasoline, or the combination of both. Thanks for the input.

L-Man