My fuel gauge is possessed. I was on empty then as I was driving, it indicated half tank, then full tank, then going erratic and finally telling me again tank was empty. I filled up, strange thing, I was able to put in 87 litres per the gas pump but normally it stops at 80 litres. I'm guessing my fuel gauge indicator is broken or what else is going on? Is there a quick fix I can try to avoid high repair costs? I heard try to put a bottle of STP in fuel tank to clean it??? Not sure what to do. Help.

 

the sending unit might be bad. that would mean dropping the gas tank, changing it out.

 

Had the same problem with the fuel gauge and also the temp gauge on my 2004 Venture. Fixed both by calling a fellow who repairs the cluster here in Ft Worth. I live about 45 miles form there and he came over on a Saturday morning and replaced all three motors (Fuel, Speedometer and temperature, calabrated it and was done in 45 minutes and cost less than $160. Seems the servo motors they used have been replaced with more reliable ones. The gas gauge jumping up to full and then down again could indeed could be the sending unit in the tank. I diagnosed this problem as the gauge because of another bad gauge and the fact that the low fuel light did not come on when the indicator showed below empty. Only came on when I was about out of gas. That told me that it was probably the meter not the sending unit as the light should come on when the sending unit was not working properly. Good Luck!