Well ive had this problem since i bought the car, but used my trip meter as my gas gauge before, but sincei m going to do the trap door soon when i put in my 255 pump i was wondering what i need to change to fix this problem.

symptoms: lodged at full from the point its filled, until it gets to maybe 3 gallons or so left... then it just kind of bobs back and fourth depending on the surface im driving on. So what do i need to replace? part number would be great. and is it easy to replace with the trap door opened up and the stock pump out.

Thanks guys.

 

The level sending unit and float assembly is riveted to the fuel pump support bucket. When I had to replace my sending unit about 8 years ago, the only way to get a new one was to by a new fuel pump bucket, about $250. Then, since my original bucket was already modified for a Bosch in-tank pump, I had to drill the rivets out of both sending units, and swap them over. By now someone may be selling a replacement sending unit.

If I read what you are saying correctly, its staying at full until you are down to about 3 gallons in the tank. While the normal condition is for the tank to only have about 5 gallons left at "1/2", and only 1 or 2 gallons at "1/4", your problem would appear to be more extreme. May be a faulty sending unit, but you might want to verify that by measuring the resistance of the unit at various fuel levels.

Use this reference, courtesy of Shoebox:

http://shbox.com/1/4th_gen_tech2.html#fuel_gauge

 

yea, i saw that, and ill do the tests when i get the battery back in the car enough to test some wirign things im doing in the car. appreciate the help, gm just never seems to make things easy enough for us.