when I bought this truck off craigslist in the fall we knew the gas gauge doesn't work for the rear and the front tank doesn't work at all. the rear gauge would be stuck right on full and barely budge but one day about a month ago it actually started working!(even though it would stick where it was when turned off) but then about 2 weeks ago I started up my truck and the needle shot all the way up, im talking like an inch pass the full line and hasn't moved sense. any suggestions? also any suggestions on the front tank would help too. thanks!

 

Sounds like a bad ground.

 

how do I go about fixing that