Fuel Gauge Misbehaving

[Hugh]

Recently my fuel gauge would randomly peg itself all the up beyond the Full line. Then after driving awhile it would "reset" itself to the normal reading. This got annoying after a while and being that the car is 23 years old with 270K miles I decided to replace the sending unit in the tank. As a side note, the low fuel warning light in the dash also stopped working a long time ago so getting access to the sending unit would allow me to run the diagnostic on that circuit too.

I replaced the sending unit and shorting out the YEL/BLU wire in the connector did not make the light go on indicating either an open in the YEL/BLU wire, no power to the guage or simply a bad bulb.

Anyway back to the gauge and the new sender unit. The intermittent gauge pegging is still there which could mean that YEL/WHT wire is shorting to ground somewhere along the circuit. Or is there something else I'm missing. The gauge itself doesn't appear faulty is you go by the testing procedures I followed in the service manual and ETM. I know it's not a good thing to have the YEL/WHT wire to ground for an extended period of time as this pegging of the gauge can damage it.

Does the fact that the low fuel warning light has not been working a clue to a potential problem in the cluster? I want to try to solve this without removing the instrument cluter as that is a major pain in the ass. I can live without the low fuel warning light and to a lesser extent without the fuel gauge but I do enjoy everything on Charlotte still working as if she were a new car.

Thanks guys,
HH

 

[Briank]

Hugh

Unfortunately, nsx gauge clusters have capacitor issues like the amps and ccu's. When they fail weird failures come up.

 

[Hugh]

Thanks for the info Brian. Do you offer a cluster "refresh" service by any chance? And if so at what cost please?

Cheers,
HH

 

[Briank]

Yes, $100

 

[Hugh]

Thanks Brian. I'm out on one of my late drives at the moment. Will PM you later to confirm delivery and payment info.
Thanks,
HH

 

[Old Guy]

The fuel gauge is a pretty dumb-ass simple circuit. If the rest of your instrument cluster is operating fine, I would first be inclined to carefully examine the wiring harness between the cluster and the tank sender including the terminal connectors looking for chafing or other signs of broken wires or loose terminals (including the ground connection at the tank). It would be a hassle to R&R the cluster to replace capacitors to find out that the problem is still present.

If the cluster is demonstrating other signs of erratic behaviour, then go ahead and consider sending it out for repair

 

[Hugh]

The only issues that are cluster related are the aforementioned fuel gauge issue and the probable certainty that the Low Fuel Warning Light bulb is bad. Everything else works fine. I re-read the diagnostic procedures for checking the gauge, sending unit and bulb and it does mention checking the ground connection. Since I still have the bulkhead trim panels removed, I'll yank the access cover again and check for chafed wires, shorting and integrity of ground before taking further action.

Removing the cluster is a PIA since I've done it before when I first got the car to reset the trip odometer. A previous owner must have tried resetting it while moving and it got stuck at the ubiquitous 363 mile mark (or something similar). However, BrianK is an electrical genius and sending him my cluster for a refresh is in itself a great idea considering the age of the unit and the fact that Brian can run a full diagnostic on all of the sub circuits and whatever other magic he performs.