Gas gauge at 3/4 tank to empty gauge drops or goes up/down and then goes to low fuel warning, changed fuel pump twice along with dash cluster twice. cluster was absolutely defect immediately,lighting up like pin-ball machine and shutting down allgauges,incldg.speedometer/odometer 2nd one light up abs/emergency brake when driving

SOURCE: gas gauge

The float that moves the gas hand is possibly stuck in the tank. If there's isn't an access hole in the rear of the vehicle you'll have to drop the tank. Unless it becomes free on it's own. Hope this is helpful. Please rate. Thanks

SOURCE: gas gauge on 2006 gmc envoy says empty after fill up

this is a giant comon problem right now with gm vechiles it is in the fuel sending unit the unit needs to be replaced ( about 400$) and the gas tank needs to be dropped out to get to it for many more people with the same proble go to topix.com there is about 96 of us with the same problem

SOURCE: 2006 GMC Envoy gas gauge not functioning properly.

GM had a problem with the fuel sending unit cards inside the fuel tank,If you replace that you should be good to go.

SOURCE: The fuel gauge doesn't read right, makin' low fuel light flash

if the fuel pump is all in-tank; the sending unit built in to the fuel pump is most likely malfunctioning; if so, this will require removal and replacement of the entire fuel pump, sometimes expensive, others not so much

Testimonial: "thank you very much for the help"

SOURCE: GMC envoy after I filled gas tank the low fuel

You will need to replace the fuel level sensor which is in the fuel tank.They have a lot of problems because the metal fingers on the sensor wear off and gives you the incorrect readings.This will also cause the check engine light to come on.You will probably have a level sensor code.This will be a lot easier if the fuel level is down to about a quarter tank or less.Also you should be able to get just the level sensor and not have to get the complete fuel pump module.Good luck.