So I decided to finally fix my fuel gauge.
Bought a new sending unit and replaced the old one....nothing happened.

After being put off for a few days I took out the instrument cluster and "clean" the fuel gauge pot up ..or lubricate it...I was bound to find something!!

Nothing!! The gauges look like they are hermetically sealed. I cleaned the harness contacts and contacts they meet and removed the green lenses for an awesome improvement in gauge illumination.

After some more dismay and rummaging the net I found it had to be my anti-slosh module, which is 60-70 dollars . I found a post where someone took it apart and re-soldered it with success and decided that was now my mission.

Only my car is an 88 and I gather it didn't utilize one.

I am assuming it cannot be the relay for the fuel system because they allow it to operate..which is does fine. What the hell is left?? There isn't much to the system, I have replaced and cleaned what I can, checked the ground at the sender and confirmed voltage coming from the harness.

What could possibly be left?

 

Remove the sending unit wire from the sending unit. It's light green/orange. Turn the key "on" and ground the wire.

Does the gauge go to "Full"?

If yes, then it can only be the sending unit, as you've proven that everything else is OK.

If no, and since you've already confirmed voltage supply to the gauge....

1) Open circuit....somewhere.... on the light green/orange wire.

2) Faulty gas gauge

When you installed the new sender are you 100% sure you didn't reverse the sender wire and the low fuel light wire? Just a thought.


That's all I can think of.

Cheers
DD

 

The Great Palm's Book has a good section on the instrument cluster. The gauges actually do come right out. They are fed power and earthed by a VERY indirect somewhat gimcrack route, including a small screw that makes the connection to the gauge itself.

As Doug said, try earthing the tank sender wire, and the low fuel light wire to see if that works as well. If nothing, remove the instrument cluster, earth the sender and see if there is power at the relevant pin on the large cluster plug. If so, it is the path to the actual gauge via the blue plastic circuit 'board', or the gauge itself. Once the cluster is apart (do it on a white sheet so any little bits you drop are easily seen) chnaging/cleaning the actual individual instrument is not hard. Also, the actual pins on the instrument cluster plugs can fall back and not make good contact with the blue circuit board, or the copper film on the circuit board rub away where the plug mames contact with it. In which case a small bit of kitchen foil will repair it.

Greg

 

Not worried about how its wired, I have tried all combination and it does the same thing. Ill try grounding it today. As I recall the correct configuration is the sender wire goes on the bottom with the light being on the right side and ground on the left. I kind of think it could be the wiring because my low level light seemed to be accurate. If this is the case, is the wiring in the instrument cluster the only leftover problem?

I know the gauge itself works because something got crossed when I first plugged the panel back in and the fuel and oil gauge went up to max when I switched on the headlights.

Now all is acting normal except the fuel gauge. There are about 5 gallons in the tank, so it should be obvious.

 

Your cluster isn't sufficiently grounded! Classic symptom.

Add a redundant ground wire. Can't promise it'll fix your fuel gauge but it needs to be done anyway!

Cheers
DD

 

So I grounded the fuel sender wire and the gauge went to just above 3/4 (wth?)

When it was improperly connected it DID max out so I know the needle isn't stuck or anything.

Where does the gauge cluster need to be grounded? Was about to just make a wire going to one of the nuts on the back but realized those aren't necessarily grounds and it could mess something up.Do I need to check the harness plug for a ground and try to connect the same section of the circuit on the blue panel?

 

At the back of the cluster you'll see a horizontal metal bar. I can't remember if it's at the top of the cluster or the bottom.

Anyhow....

Attach a wire to the bar....I recall a handy screw at each end.... and run it down to a convenient ground point under the dash. If you find an already existing ground point that's fine....but make sure it's clean. They're often corroded.

That's it :-)

Cheers
DD