When I bought the 71 Delta, the gauge read between 3/4 and full. One mile later, it ran out of gas. I got to a gas station, filled the tank, the gauge never moved. I've driven the car a little, and recently topped it off with 11 gallons. This car sat for a long time. Is the float stuck? Is the gauge itself bad? It's cold in NY, I haven't been able to get under the tank yet to look around. If either the sender or gauge is bad, or a bad connection/ground, wouldn't it read past full or empty? Any comments are appreciated. Thanks.

 

My guess is the float is stuck and full of varnish. If you take the wire off the sender at the tank that runs forward to the gauge and ground it to the frame with the key on, it will go to E on the gauge. If you just remove the wire it will go past full.

 

Likely yes its stuck, and likely no the gage is not bad.

X2 I had that problem with my 78 Cadillac. Dang thing would run out of gas still showing 1/2 tank.

I doubt it's the gage or the wiring. You're going to have to drop the fuel tank to fix this. Time consuming but not terribly hard. It helps if you can get the rear of the car up in the air at least 18-20" and fully protected with jack stands or safety supports.

1. drain the tank
2. disconnect the ground, sender wire, and any tank vent rubber hoses. (replace the rubber hoses when you re-install. IIRC they are 3/8" on main line and 1/4" on the return line.
3. start the bolts that hold the tank (4 - 2 front and 2 rear) They can be really rusty, so be prepared to replace them. Use some penetrating oil to lube/soak the bolts and threads for a bit first.
4. position a lift and a bit of plywood under the tank and lift till it contacts.
5. undo all the bolts.
6. drop the tank down and forward. It helps if you have a helper. The filler neck may bind on the rear frame if the car isn't high enough.
7. remove the sender locking ring and carefully remove the sender. I'd just replace it with a new one at this stage. The senders are available from your auto parts store. Most new senders come with a new rubber seal and locking ring, but don't throw your old one out till you know the new one fits. Rockauto has them for around 55.00 + shipping


Just an FYI, O'reilly's sells the same unit for 75.00, but if shipping from RA bumps the cost to that? Support your local parts shop.

Reverse the procedure and put the gas back in. Enjoy knowing when you're going to run out of gas next!

 

Very helpful, Thanks!