After my racetronix fuel pump install last fall my gas gauge will only read 5/8 full with a full tank of gas. It goes back down to empty like normal as I run out the gas. I dropped the tank twice last weekend and pulled the pump sending unit out, it tested out normal ohms by moving the float arm up and down and no hoses seemed to obstruct its movement. Has anyone else had this problem and if so how did you fix it?
Is it possible the buoyancy of the float to decrease with age and not allowing the float rod to go to the top with a full tank of gas, thus showing only 5/8 full on the gauge?

 

I finally fixed my fuel guage problem after dropping the fuel tank for the 3rd time. Everytime I took the sending unit out and tested its ohms it read correctly until I reinstalled it. So I took the tank out completely the last time and looked inside to see what was keeping the float from moving completely up to the full position. The tank has a metal support like baffle right next to the float, somehow my sending unit bracket got slightly twisted by the hinge spring (probably on removal) and when the float would raise up it would hit the support keeping it from going all the way to the top of the tank. I twisted the sending unit bracket back to normal so the float would raise parallel to the baffel and not rub during movement, connected jumper wires to the car connector and tilted the tank up and down simulating gas in the tank. Finally the guage would move from full to empty, so I put back the million parts of the rear end and exhaust and I'm good to go.
Moral of the story is cut the access hatch or be gentle removing and installing your fuel pump if you use the drop the tank method. Sorry about the long winded post, just hopes this helps someone else so they don't go thru this as many times as me!

 

Good info, Kevin! I've had the same thing happen to me when removing the pump/sending unit. This is a common issue. Thanks for posting the details!