Hi.

I've had what seems to be a grounding issue for quite a number of years now. I've been ignoring it. It exposes itself through the gas gauge. The needle sways back and forth when any current is drawn, like a turn signal, brake light, power window, etc. The more the gas tank is filled (the higher the voltage reading on the gas gauge), the more it sways. Attached is a video to demonstrate:

https://drive.google.com/file/d/0B1Z...it?usp=sharing

I've never diagnosed a grounding problem before. Any ideas on where to start?

Thanks!

Vehicle is a 1997 Chevy Blazer 4WD

 

Start with the ground strap for the fuel pump/sending unit, It is located at the very rear of the truck in the middle.

To find it easier, look between your wheel and wheel arch and find the fuel pump, follow the fuel pump harness back and it should be attached to a cross member

 

I believe the fuel pump on this vehicle is inside the fuel tank.