My fuel guage has been acting funny. No not yelling jokes at me! :P It started to not go all the up to the full mark. When full it has been recording only about 3/4 of a tank. Now when full it only shows 1/2 a tank and never drops below a 1/4. I guess I need a new sending unit? Never replaced one before. Is this a simple task? Please don't tell me I have to drop my tank. 1970 El Camino.

Thanks for the help....dave

Yes you must drop the tank. I changed one on a 69 chevelle .

have you checked your tank for obvious damage? Years ago i ran over something and dented the tank. something simple to check.

Hmmm will check it out....Thanks guys for the info. I will keep you up to date on what I found.

Almost sounds like the calibration resistor has gone bad. That's the white ceramic thing on the back of the gage. I'd test the gage first by opening the sender wire. Disconnect it from the tank. It should read super-full. Short the wire to ground. It should read empty. If it reads around 1/4 tank, change the resistor on the back of the gage. Any 70's pick-up truck should have one and not that hard to pull from there.