1988 fuel gauge not working

[woody31]

like it says,,fuel gauge inop,,reads past full..what color wire do i ground to check the gauge/sending unit...i located the plug,,wiggled it and no obvious signs of trouble,,what is the best way to check this out,,,thanks

 

[woody31]

bump,,anyone,,16 veiws and no reply??????? i did try the search feature on this forum and not much help.,,i need to know what color wire to ground,,,the plug is in reach,,i just need a reference ,,and yes i did try google,,and another forum,,so far no luck,,any help is much appreciated.,..

 

[woody31]

up date ,,if i ground the pinkish wire,,with my test light it lights up real dim,,and the gauge goes to empty,,soon as i take the probe off it goes back to full????any ideas???

 

[great white]

http://www.gmtruckcentral.com/wiringdiagrams/1991.html

Not an 88, but should be same same...

 

[woody31]

thanks for the link,,but that does not help me much,,,i have power..and when i ground the pinkish wire the gauge goes to empty,,when i remove the probe,,it pegs on full??? anyone??

 

[great white]

Actually, the link helps you quite a bit if you know what you are looking at.



The probe in the tank is essentially a variable resistor. The float moves the contact point.

Messed up sender, messed up guage. If the guage sees a full 12v or 0v, its going to read appropriately. Which seems to be what you are doing with grounding the sense wire.

If I get a chance today I'll dig out my old 1989's FSM and see what the diagrams look like.

But, faulty senders are a common problem on these vehicles.

 

[woody31]

the sender was replaced last year ,,i suppose it could be bad,,,thanks for your time g.w.
electrical is not my forte" i guess by what ive done so far it is pointing to a faulty sender???

 

[great white]

So, pulled my old 89 manual out and checked the trouble shooting chart.

-----Symptom-------------------------Probable Cause------------------------------------------Correction------------------

Gauge stays at "E"---------------No fuel, Grounded circuit---------------------1. Fill tank (duh)
-----------------------------------------------------------------------------2. Disconnect lead at fuel tank the gauge should read past past "F".
--------------------------------------------------------------------------------If does not read past "F", replace sender. If stays at "E", find --------------------------------------------------------------------------------short/ground between gauge and tank

Gauge stays at "F"----------Open circuit between gauge and sender---------Disconnect sender lead at tank, ground lead. gauge should read "E".
---------------------------------------------------------------------------If gauge reads "E", replace sender. If gauge still reads "F" or beyond, ---------------------------------------------------------------------------find and repair the open between gauge and tank


The third step in the chart is if gauge reads wrong, but that's not what you have going on here....

The sender is like every other GM fuel sender, it has a resistance of 0-88 ohms. 0 is empty, 88 ohms is full.

 

[woody31]

ok sounds like a plan..i cant thanks you enough for your time and replies,,,i hope you have a good rest of the weekend,,,cheers,,g.w.

 

[twomanymontes]

From what you described, it sounds like the ground wire is open. Or the connector or wiring between the connector and the sending unit is damaged. Using the test light proved out the gauge and circuit is good.