fuel gauge not workinng on 2005 GMC Envoy

About 4 months ago my fuel gauge quit working. I had fuel sensor and pump(for good measure) replaced. Now the gauge quit workinmg again, but this time it sits pointing straight down - is it the dashboard gauge? Also, check engine light has been on lately.

by in Helendale, CA on November 29, 2010
2 answers
ANSWER by on November 29, 2010
Start with the code for the Check Engine Light just to eliminate that as a possibility. A good way to check a gauge is with a gauge sweep tester. See if you can borrow one from a parts store. As a Pro, I would read the instrument cluster data stream and see if that agrees with the fuel level sensor reading. Then I know and don't have to guess.
ANSWER by on October 31, 2012
My 2006 Envoy had the same problem. Before you go to GM dealer for $400 repair, check and re-ground fuel system wiring harness. On the driver's side frame, just below pasenger door, there is a ground lug bolted to the frame. Remove it and sand down both the lug and frame around the hole. If you can, put a internal-external tooth lock washer between the car and lug. After tightening it down, apply silicone grease over it. Check to see if it fixes the problem. I was into replacing the sensor by dropping the tank when I found the connection, and it was very rusty. here is a link to a source for that washer- http://www.zorotools.com/g/Internal%20External%20Tooth%20Lock%20Washers/00056681/