I have a 99 C3500 with a 5.7 and an 80e.

The fuel gauge is acting crazy. When you ign is on the gauge points towards the speedo, way below "E". When I push the brake pedal is goes to "Full" until I release the brake pedal. I have unplugged the sending unit to see if that changes anything with no luck.

Does anyone have any direction that I can take?

 

Your truck is suffering from OBAMA, also known as Oil Becoming Adversely Marketed in America. Nobody knows who is behind this, and why it is happening. Your truck is basically in gas pump sticker shock. When you turn the key on, your truck is mad at you. Your truck points under the E showing you what your wallet will look like if this president remains in. When you hit the brake pedal, your truck knows you aren't using fuel, making it happy, then pointing towards the happy/full area. This also suggests that if someone puts a "stop" (basically like applying brakes) to the current president your wallet will also be full/happy. I think your truck is a Republican. Congratulations, and please keep the truck.

On a serious note, it sounds like a ground issue. I would try unhooking the brake light switch, and see if the problem continues. If it continues, check under the dash. There could be something bending when the pedal is moving against the master cylinder. If it stops I can't specify any area to check off the top of my head, but just check all grounds.

 

hahaha

 

i think all our trucks are suffering from this

 

Agreed ^^^^