Hey, there. It's Tim from the lake. IIRC, pegging at full means that you have no ground signal.

This can be due to a broken signal wire... in the case of my GTA, it was a lot of cruddy residue on the wiper assembly in the tank. In other words, my sending unit was all gunked up.

I know that in the older cars (I'm talking 60s and 70s here) the gauges usually operated on about 3V. We used to take a flashlight battery ("D" cell) and connect it across the gauge terminals. It would make the needle go up or down, depending on the polarity of the connection (ie, where you connect + and -). Since the "D" cell was 1.5V, it would make a properly functioning gauge read about half with the correct polarity.

I don't know what voltage the thirdgen gauges operate on, but you could try the "D" cell and see what happens. If nothing, then try two in series. If the gauges work on 12V, that should give you at least some movement, and I am guessing with correct polarity it would give you a reading of around 3/4 full.

 

hey. but what about the firmness of the needle? and also if i had a bad ground wouldnt other things be affected to?

 

That gauge has a stiffer needle because of how it operates.

The sending unit in the tank applies a ground signal through a variable resistor to tell the gauge where to move the needle. If that signal is totally absent, you get a 'full tank' reading. Since the gauge is grounded through the sender in the tank, it does not affect anything else. All other indicators are grounded to the chassis.

 

aaaa and i suppose to find the no ground singal would be to drop my tank...?

 

 

umm car running, or in on postion? and umm...where do i find these wires?

 

 

well finally got my hands on a ohm reader and interesting thing the wires coming from the sender they tested at 88.7 ohms after a few seconds of bouncing between 80-120. ok wtf? the tank isnt full (i dont think)(but it might, trying to figure out the dieing problem) but anywas so then im like hmm the gauge? so i tested the same wire connectors on the gauge cluster and after extreme jumping it settled on 166.3 ohms...ok wtf? a 0-90 ohms gauge at 166...so im thinking (with others) that the guage is bad. i just want to make sure before i go and buy a new gauge.

 

ok so today i topped off my tank, took in 7 gallons (12 gallon tank) which menas yesterday it had 5 gallons so it should of read 45ish ohm oppsed to 88 right?

 

 

so bad gauge and sticking float is what im thinking (gauge at 166 ohms, and float at 88 ohms on a half full tank)