Fuel Gauge Help! (Fixed)

[Blake]

Hey Everyone,

Having only owned an 82', i havent had experience with diagnosing whether a fuel gauge is bad, or the tank sender.  I looked up some info online, but it hasnt helped me any.  here's my problem.

To make a long story short, I had taken the dash off my old cadillac to get at the AC box, and when i put it all back together, the fuel gauge didnt work, yet it was working fine before i took the dash off.  i drove a few times with it off, but since this baby guzzles gas like it was going out of style, im a little worried to drive it anymore before i get that fixed.

Looking through the factory manual didnt provide much help.  Basically it said to get a new tank sender, hook it up, if that doesnt work, replace the gauge.  I did find out that the sender is 90ohm full, 0 empty. to see if the sender was bad i went and disconnected the wire from the tank and used an ohm meter to see if i was getting any reading.  I got about 62ohm, so around 2/3 full, which is pretty much right where it should be (thats where i filled it up to).  so i assume that working.  then i went into the cabin and ohmed the wire from the sender to the ground.  again got about 62-64 ohms.  so i assume the sender is fine.

One thing i havent seen before on fuel gauges, is there are three posts on the back of this one.  There is a tan wire (to the sender) a black wire (i assume another ground?) and a pink wire (which on the wiring diagram looks to be just a power lead.  Leaving the connector on the gauge, i jumped a 12v wire to the pink post, but nothing happened (except a buzzer went off under the dash (sounded like the one to remind you to turn off the headlight).  but when i checked for voltage from the pink wire to the black, nothing.  i replaced the fuse and checked again, nothing.

Online i saw that some gauges say to ground the sending post, but on those 0ohms is full.  would that still help me see if the gauge itself is bad?  I was thinking of picking up a potentiometer from radioshack and adjust it to 90 ohms to see if maybe thatll do anything?  as you can see im clueless.

Im pretty much at a loss here.  Cant go out and buy a new oem gauge, but if this one is bad, im going to have to go get some cheap knock off from autozone until i can send this one out to get fixed somewhere.


If anyone has any experience with diagnosing a fuel level gauge, id really appreciate some help.  Im not sure if theres some power source problem or if the gauge itself is bad since i really am not sure how the gauge works in the first place (reads ohms to ground? or some sort of voltage meter basically?)


Thanks a lot,

Blake

[Walt_M.]

Sounds like the black wire on the gauge isn't connected to ground.

[Blake]

Well..  i figured out the problem..haha.


I connected the black wire to the negative battery cable, pink wire to the positive, and the gauge moved to full.

then i touched the "Tan" wire to the battery too. it moved down to empty.  so it works. so that lead me to believe...no power.

But i kept changing fuses...  30 year old fuses.  haha..

went and bought some new 5amp fuses, slapped one in, turned on the car.  presto.


guess for certain parts, oem just wont do :)




Blake