Pontiac Repair: Montana fuel gauge, fuel level sensor, montana fuel

Question
The fuel gauge on our 2002 Montana is erratic, always shows full but goes to empty when sitting at idle for about 1 minute. Sometimes it goes back to full once we start driving, other times it stays on empty until the car is turned off and restarted. This problem happens even when the car is not running but key is in the run mode. I disconnected C305, put ignition in run mode and same thing happens. It seems as though it's not fuel sensor issue.

Answer
Hey Ralph;

You did a good job of figuring it out. it's a fuel level sensor that is bad. very common. Due to the sulfer content in the fuel it eats away at the contacts on the fuel level card. That is replaceable seperate from a whole complete pump. you need to drop the tank and take the pump out to get to the level sensor but it is a lot cheaper then a complete unit. Use only a GM ac delco replacement part. Also a couple of times a year use GM fuel system cleaner/treatment it will help protect against level sensor failure in the future.
good luck :-)