mupepe

So my fuel gauge or my sending unit isn't working. Can anyone describe how I would go about finding out which one is borked? The fuel gauge just goes all the way up (past F as far as it can). What's some troubleshooting I could do?

blckslvr79

Make sure your tank is not full of fuel????

Alan 71

Hi m,
Since your car has been modified I believe it would help if you described the tank and sender to help determine what it is. They changed over the years so the trouble shooting procedures changed too.
Regards,
Alan

You may want to check this thread.

http://forums.corvetteforum.com/c3-t...e-testing.html

mupepe

hahaha I was actually fooled the first time I drove it. I was like "ooh full tank!" Until I realized it hadn't gone down and I realized how easily I could have ran out

mupepe

the gauge seems to be original. It matches all the others and pics I've seen. But I'll take pics of it tonight too and show you guys what I have. And... I don't even know where I'd find the sender. I'm sorry. I'll check out that thread. Thanks

...Roger...

Gauge going to full usually means you have no input signal from the tank sender,one reason for this is the wire might have fallen off the sender.

Rebelrob

I had similar issues with mine, never actually resolved them either. I did all the ohm testing, pulled the sender out of the tank. It worked fine out of the tank, go figure.... but it would only go from F to 1/2 and then stop when back in the tank. I checked the tank for interference to ensure nothing was hitting the sending unit arm. Such as some tanks have rubber bladders or whatever. Still puzzled as to why I get that fubar readings. But I am busy with an engine build and the issue has been shelfed for now.

70454

Mine is stuck at 1/4. Doh!

ssenay72

I wiggled the wires at the tank top and it works now. LOL

EWJammer

1979 Sending Units operate between 0 - 90ohms of resistance. Disconnect Sending Unit wire from top of gas tank - Gas gauge should peg past full. Touch the disconnected wire to ground and the Gas gauage should peg past empty. If the above indications are valid your sending unit is defective.
EWJammer - SD

shrekviper

Willcox has some help.

This one's for 68-76, they have others. Just search their "Install & Repair Help". A lot of good info in there.

http://willcoxcorvette.com/repairand...lp.php?hID=276

Rebelrob

Here is a dumb question for tonight. I have similar problems with fuel gauge. The gauge works perfect when I have the unit out of the tank and do all the ohm testing, etc.
I did the string test. Tied a piece of string to the sender unit arm. Reinstalled unit back in tank. When I pull on the string replicating a full tank, fuel gauge goes to full. When I let go of the string I hear a clank. The tank has about 10 gallons in it. So I should not be hearing a metallic sound when I let go of the string.
The dumb question is- can a floater go bad (aka stop floating?) Sure sounds like that is the problem. Like its sinking right back to the bottom.

EWJammer

Either you do not have 10 gallons of gas (you said you hear a clank - that sounds like the bottom of you tank) or your sending unit is not floating. Since you already have the sending unit out test in a bucket of water and see if the float floats. By the way, Your low fuel light should light at 2 gallons as well.
Rob - SD

Rebelrob

Well it is definately hitting something, which makes me thing the floater is not working. Not sure if that is possible, but the unit works perfect outside the tank as far as the gauge goes. I will have it removed here in the week or so, and I will test the floater. I was just wondering if anybody has ever had this problem with a floater.
Thanks,

AutoFast

Bringing this thread up again add it didn't really help my situation. I connect a wire to the center ground on my temp gauge and over to negative terminal on my battery. I connect another wire to 12v terminal on fuel gauge and positive terminal. The gauge went to 3/4 full. Is my gauge bad? It the tests recommended I either bury the needle past E or drive it to 3/4.

​​​​​​​help?