fuel gauge stopped working

[cars463]

I left home with a quarter tank and it just went to the bottom suddenly. All the fuses are good and the signal wires are still connected. Does anyone have ideas?

[BerniniCaCO3]

I've been doing my research because my own fuel gauge has problems (albeit different ones).
What year is it?
1986-89 has low high resistance=empty, 1990-91 has low resistance=empty.

So if it just all of a sudden plummeted to empty, then if you've got a <1989 car, you'd expect an open, a poor connection somewhere, corrosion in a wire, etc.
And if you've got a >1990 car you'd expect a short to ground.
Alternatively the sending unit itself could be stuck, with the float sunken, but I wouldn't expect that to be quite a sudden thing. The variable resistors in the sending unit can have dead spots also.

With a basic multimeter, measure the resistance right now across the two leads coming from the sender at a quarter tank, then fill it up, and measure again; that'll give us an idea of whether the sending unit is A-OK.

Next check power and ground.
Check voltage on the signal wire hot, to ground, just to verify that there's something. My wires were just black and I couldn't tell you which is which, but one was at 0V and one had voltage, so just measure both and you'll know. If they're both at 0V then power isn't making it to the sending unit.

Those are the easiest steps, since you only need to crawl under the fuel tank and look at the wire.
If all those things check out: sending unit shows plausible resistance values at two tank levels, AND the gauge does not move when you refill the tank, the next step would probably involve locating the anti-slosh module, which negotiates between the gauge and the sending unit, make sure power is present at both ends (going to the sending unit, going to the gauge), and check the ground. In <=1989 it's above the glovebox, easy to find once the glovebox is out. 1990-91 I haven't checked yet, but I've got the manual now and can look it up for you.

[Mainemantom]

The sending unit in the gas tank could be bad, or the float got filled with gas. As least you don't have a full tank of gas if you have to pull the tank.

[cars463]

Its an 84. Ill have to check out those things later but it was really weird because it just dropped and the low fuel light turned on.

[86VickyLX]

Float. Pull the sending unit. Little tin looking thing on the end of the sending unit. Has a hole in it. Full of gas, if not, the senders bad. Either way it has to come out...

[Brandon]

Try swaying the car left to right going down the road and see if the guage will try to read the gas level. If does go back up then its your sending unit. Just be careful and only do that at slow speeds! Don't sling the car into the grass!

[cars463]

i measured for resistance across the post and the was no reading. but there was voltage from the wires. so id assume thats a problem with tht esending unit. does anyone know who carries a replacement piece?

[86VickyLX]

i measured for resistance across the post and the was no reading. but there was voltage from the wires. so id assume thats a problem with tht esending unit. does anyone know who carries a replacement piece?

Good luck with that. That stuff is all obsolete.

[cars463]

yeah youre right. i was gonna do a fuel cell but i just put in a new tank instead. it had been leaking. so i guess ill just go by the trip meter. thanks for all the input though

[1987cp]

I've seen sending units for sale, but only separate from the mount or pickup tube, so it'd be up to the end user to get the potentiometer bit mounted correctly.

[BerniniCaCO3]

What do you mean by that, precisely, 1987cp?
Would this guy just be plug and play?:
https://napaonline.com/Catalog/Catal...P_RecType%3aA)

The industry price --just tell 'em you work for some shop, whether or not you do, they don't give a damn-- is always roughly 1/2. So $100 for the above item.
Mine has slightly high resistance, wondering if I should replace it too, and while I still can!

[1987cp]

What I was referring to is only the potentiomer and float, without the tube and mounting plate. I've seen that assembly before on Fleabay and I want to say from a couple of parts sources.


What on earth is that thing you posted a link to?

[BerniniCaCO3]

I was hoping you could tell me
Did it open for you? I retried it, the link works.
That's what comes up for a sending unit when you browse NAPA.

It has a float, at right angles to the backing plate, which looks like it's included in the assembly.

[1987cp]

Well, yes. But what's it supposed to be for? It doesn't look a thing like any fuel level sender I've seen.