MCMLXXX

Hi guys,
Got a question about my 80s fuel tank.
Did the 1980 have a bladder inside the tank?
when my fuel gauge gets down to 1/4 tank I fill up, but can only get around 13 gallons in the tank, and the 80 is supposed to have a 23 gallon tank. so is it my fuel gauge? or is the bladder(if it even has one) messed up. if i still have 10 gallons left in the tank the gauge should read somewhere close to 1/2.

Thanks,
Mike.

c3corvettes

Might require some basic electrical troubleshooting between the fuel sending unit and the fuel gauge. You could also go the other route of trial and error. Replace sending unit inside tank. Then replace fuel gauge if problem still persists. Someone more knowledgeable on the forum will chim in and help you out. Hang in there. I'm not sure what the "bladder" is...

qwank

I had the same question. When my low fuel light comes on, the needle is pretty much at dead empty, but it only takes 19 gallons to fill it.

gbvette62

GM claimed that the 80 tank was 24 gallons, not 23, and yes it did have a bladder in it.

My guess would be that you have a problem with either the gauge or the sending unit.

Usually if you have a leaking bladder, you will run out of gas, with the gauge still showing gas in the tank. Fuel that leaks out of the bladder, ends up trapped between the steel tank, and the rubber bladder. When this happens, you end up with 5-10 gallons of fuel trapped under the bladder. As you use the fuel up, the the sending unit's float keeps dropping. At some point it will come to rest on the bladder. The gauge will show a 1/4 -1/2 tank of gas remaining (it is there, it's just under the bladder), yet the car runs out of gas, because there is no fuel left in the bladder to pick up.

I won't say that you don't have a problem caused by a leaking bladder, but if you had 13-14 gallons of gas trapped in the tank, I think you would run out before the gauge got down to a 1/4 tank.

bozzman3

I could be wrong,but I recall reading somewhere that Gm would set up the fuel supply system with a 2 gallon reserve.When the gauge read empty there was still 2 to 3 gallons left.I have a low mileage 1980 and when its almost at empty it only takes about 17 to 18 gallons.I thought it had a 18 or 19 gallon tank!

qwank

so mine must be correct then. when the light comes on, there 5 gallons left.

MCMLXXX

Thanks guys, That narrows it down for me then. i am sitting on empty right now so when i fuel up I will see how much i can get in there.
the owners manual shows it being a 23 gallon tank, So that is what i am going off of. I was hoping it was something like the sending unit and not the bladder. Thanks for the help!

Mike.

Grumpy 427

I have an 80 vette, and my gas tank was a plastic fuel cell inside and not the bladder. I was greatful i didnt have to deal with that bladder BS. I wonder if there was a change part way through the build year?

KENS80V

78 to 82 tanks have a plastic liner inside the tank. They don't shrink like the rubber bladders did in past models but they will eventually dry rot and split. Replacement tanks do not have the plastic liner.

First thing I'd try is a can of Sea foam or Techron in the tank. It might clean up the contacts on the sender.

'75

I just had a 78 tank out and it has plastic on the inside. The plastic is actually pretty thick and the metal on the outside is very thin. It reminds me of a plastic tank with a thin metal shell. I think the plastic is too rigid to collapse like a rubber bladder would. I can't imagine it would get very much fuel between it and the metal shell even if it split.

Yellow1980

When my 1980 gets down to 1/8th it takes 16 gallons to fill it up. So it sounds like that may be normal for a '80.