Anyone ever have this issue?

Not sure where to start.

Does anyone know what fuse is for the sending unit?

I checked the wires at the tank and they seem to be connected.

Any ideas appreciated...

Thanks

Do a search on the site there have been some good discussions about this. I had the same problem and they had to pull the gauge cluster and clean all of the contacts to get it to work. You should also check the ground from the sending unit, mine comes out of the front of the tank and connects to the frame so you will need to get under the car. Good luck.

Hey, at $2.50/gal don't complain!

You must not be in California.

It is over 3 bucks for regular right now.

I will try and wiggle the wires at the gauge to start off.

reading full usually means 'no ground' or a bad sending unit

Chances are there are no wires on the back of the gauge. Connections are made by an overlay.
How full does it read?
My sending unit went bad one time and the gauge went so far to full side that I couldn't even see the needle. New sending unit and all was better.
There is a ground wire that runs from the sending unit to the frame that sometimes gets coroded and loses contact. If you get under and look up, pass side front of the gas tank near the corner, you sould see it.

Zoomed in:

Yep, All I got for trying to find the wires under the dash was a bloody hand.

The gauge reads the same as it would if the tank were full of gas, but since I did not fill it full to create this event I doubt it is a stuck float.

I guess dropping the gas tank is in order, because I can not access the sending unit from underneath, I can get my hand up in there and the connections feel fine, but in order to replace the sending unit, or even inspect it, the tank must come out.

The sending unit seems to be in the center, front, top of the tank.

EDIT:
Thanks for posting the proceedure, that should help a great deal.

If you can locate a spare pigtail AND sending unit, you can plug into the harness inside the trunk and test. That will eliminate the gauge, printed circuit and body harness from the list of suspects.

Ok so we dropped the tank, and pulled out the sending unit.
Being the kind of guy that likes to try and fix things, I pryed the sending unit rheostat open.

Everything looked ok in there, so I cleaned the contacts and put it back together.

I noticed it reminded me of a slot car controller inside.

It started to work, intermittantly.

Upon very close examination, I notice the pin where the hot wire attaches to the flat strap that goes to the rheostat on the inside, rotated on the strap.
When I took some pliers and made a positive connection from the pin to the strap the gauge worked.

Took a dremel tool with a small wire wheel and cleaned the area.

With flux and a soldering iron, I soldered the connection so the pin would not rotate on the strap.

Problem solved.

All the while my friend kept saying "just order a reproduction sending unit from year one"

I said, No, I got it figured out!

I was hoping to find the build sheet on top of the tank, but I guess someone already had the tank out and took out the sheet.

Disappointed about that, but glad I fixed the sending unit.

I kept telling my friend " If a man made it, another man can take it apart and fix it".

This was a "fun fix", and it is the kind of thing that makes owning a classic car a great hobby.

Thanks for all the help, and for the motivation to just pull it apart and see what makes it work.

Glad it worked. Have you looked under/inside the rear seat bottom cushion yet for the build sheet?

Well I have had the seat out and have not noticed it.
For some reason I thought they put them on the gas tank.

By looking at your photos, I guess you would know best.

Thanks for that, I think it was long gone before I bought the car unfortunatly.

I've found the build sheets buried in the guts of the passenger seat before and under the carpet in the rear footwell. Sometimes they were put on top of the tank. It just depends on how the guy was feeling that day that was reading them i guess.

Actually, I had the seat out a few times over the years and had not noticed either. Someone here (or on the 1st Gen List) had said they can be tucked well up into the springs so I looked again. It was there and hidden by that felt sound deadener.

I will look again.

My car was built in California.

I gotta believe that different assembly plants put the sheet in different places, or like was mentioned maybe whoever was the last to have it put it where they wanted to.

Since I bought my car in '85 for $800 at a garage sale, the chances of it still being with the car is slim.
For that price I won't lose any sleep over it.

WOW!! That was some garage sale. Didn't have any of those old Louie the 14th chairs or an old dusty Picasso laying around did they?

Funny thing is, I did not buy it the day I went to the garage sale.

A friend had a '68 vert, and came by a week or so later.

As he was driving away at dusk one evening, it just looked so cool.

I remembered I had seen one (or at least a simular one) at the garage sale.

Went back and bought it.

Hard to believe it did not sell at the sale.

Well I guess most garage sale junkies don't go looking to buy a car. More like trying to find an old set of fishing waders for a nickel.

Hard for me to believe that when I bought mine it was only 10 years old. Doesn't seem like 10 yrs is very old for a car these days. But it wasn't a classic yet just a kind of a cool old beater.

betcha they sold plastic ashtrays w burnmarks for $0.35 though!