Fuel gauge quit
 

That about sums it up. No workey. Where should I look first? I understand it's a fairly common problem, so I thought I'd ask those that have been there and done that[director] Thanks!

I'd look at the sending unit in the tank.....very common to go bad

Most likely the sending unit in the tank. Nine times out of ten that is the problem.

Thanks for the replies--I'll look there first!

Hi G1625S,
When you say the fuel gauge doesn't work, do you mean the needle isn't registering at all? Or do you mean the needle isn't registering the true contents of the tank? If it is the latter, the sending unit in the tank is probably to blame. In that case, it is common for the gauge to show about half to quarter tankful when it is actually empty. What are your symptoms?

One morning, the gauge went to empty when I had about 1/4 tank. Low fuel light on too. It started working after I filled up that morning, but only for a couple hours, then went back to empty and has stayed there for several tanks.

I've got a question on this subject. Couple years ago mine did almost the same thing and when i pulled the unit out the float that was supposed to be on it had disappered. Anybody else ever have this happen?

G1625S, I don't know a whole lot about this but it does sound like a tank sending unit problem. You may have to pull the tank and check the ohms at the sending unit or something else may be very apparent to you once you look inside the unit. Hang on, someone with more to offer will chime in. Meanwhile since I know this sort of thing comes up often on the forum, try a search for 'fuel gauge' or 'sending unit'. A lot comes up on the subject.

Take the unit out of the tank and inspect. THEN get back to us. Simple as that.

I'll be pulling the tank next week. Just filled up[duhhh] I'll try and snap some pics of what I find and post them up.

Check out this thread also:
https://www.dieseltruckresource.com/...highlight=ohms

Apparently some of the components used on the older sending units weren't compatible with diesel fuel.
The new ones are and last.
Sending unit is about $60 at the dealer. Don't let them tell you it isn't available separately and you have to buy the entire $300 module, it is definitely available separately.

What would be the problem if the fuel guage only shows full all the time?

There are a few reasons why it would read always full. First thing that comes to mind is that the float in the tank is stuck in the upward position. Sometimes that happens when over-fueling and the float becomes jammed. Ground from the sending unit could be bad. Ground to the dash gauge is bad or wire is loose or severed. Conversely a gauge that reads empty all the time could have a fuel saturated float or the float could have fallen off or the control arm could be bent from fueling with a high powered pump such as you would find at commercial fueling stations. Rapid powerful entry of fuel into the average light truck tank can bend and distort the float control rod. I know that when I took my sending unit out, the plastic covering on the float had turned gooey and the foam float would have soon become fuel-laden however, the rheostat went bad before that happened.

I'd start by grounding the fuel sender wire near the tank if the gauge goes to full It's probably the sender If it doesn't It is possibly the wire or under the dash....gauge etc. start by isolating the problem before you go after the sender