gauge reads way past full all the time, i think the gauge is done. there's a couple options i thought about but i need you help. one would be to get a brand new factory gauge which is 260 bucks in lmc. another option is saying the heck with it and fill up every 150 miles. and the option that i'm almost set on doing is getting an aftermarket gauge. i was wondering if you guys have done this and what the ohms reading is at full and empty. any help is appreciated

erik

 

What vehicle are you talking about? Are you sure it is the gauge? It sounds like the sending unit in the tank is bad which is a common problem. Have you done any tests?

 

its on an '88 bronco, i've heard from a lot of people that fuel gauges usually get warn out or bad on 80s trucks and mustangs.

 

My gauge will work fine when full but once you use some gas the gauge has a mind of its own, I was told that the float was made of dense styrofoam and eventually becomes saturated on these Broncos, thus causing a fluctuating neddle

 

The float on my FSB was made of brass and it was sinking, giving me a empty reading. I drive for 4 years putting gas in every 100 miles. I bought a new float for 79.00 which I had for 4 months before finally replacing it a couple of weeks ago. It took about a half a day to do. Getting the rusted skid plate bolts took up most of the time, and so did transfering 17 gallons of fuel (I did not know how much gas I had). Replacing the sender took about 10 minutes.

 

well if my needle always point straight over to the right all the time, even after using about a half tank, what could it be then? would it be the gauge or the sending unit?

 

Could still be either, or both. Here's how I troubleshot my 93 XLT.

The guage works by measuring the resistance across the contacts in the sending unit. Go to Radio Shack and buy a 100 ohm, a 50 Ohm and a 25 Ohm resistors. These should literally be pennies apiece if you can buy them in singles. Maybe more if you have to buy a multi kit.

Then locate the electrical connection between the frame and the tank/sender. Now take one of your resistors and bend the leads so you can make contact with whichever two pins control your guage/sender pair. (On mine it was the two skinny wires out of the four. The two thicker wires power the fuel pump itself. A haynes manual would tell you for sure.)

Turn your key to the "ON" Position. The guage should move.

Now by swapping out the 20-, 50-, and 100-Ohm resistors you should get the guage to read 1/4, 1/2, and full, roughly. (On mine full is actually 115-Ohms or something.)

If the guage moves then you know the guage in the dash is not your problem. Drink a beer and rejoice, it's your sender in the tank which for whatever reason has failed in the "Full" resistance setting and it will need to be replaced. That will be cheaper than the guage itslf.

Replacing it is a whole different article. You can find it online here somewhere.

 

thanx i will have to try that, even drink a beer after its all solved, lol, it would suck though if i have to drop that take to replace it, especially since the sender is part of the pump as well

 

Well, droppin the tanks surely does suck, but it's probably still easier, and definiately cheaper, than ripping the whole dash apart and replacing a guage. Good news is that at least the diagnosis is cheap and requires no dismantling. So at least you can find out.

Also, I forgot to mention, start by pulling on all the wires as they enter the connector. I had what I thought was a bad pump turn out to be broken wires. What got me was that the broken ends had enough connection to read voltage on my meter, but not enough to carry current to run the pump. Only takes a hair to show voltage. My sender was bad so I had to drop the tank anyway, so not too much wasted effort, but turns out all the pump needed was a new connector. Doh!