Fuel gauge stuck on Empty

[kerker]

I have a 1992 Mercury Tracer stationwagon automatic with A/C, Red with Red interior, only 60,000 miles (because I live in Hawaii) and my problem is this ........ My Fuel Gauge is stuck on empty. First, when I would fill up with gas it wouldn't go completly to Full and over the course of a couple months would progressivley go less and less to the Full position (i.e. 3/4 then 1/2 then 1/4) until it wouldn't register anything except completly empty. I sourced a used fuel pump assembly from another 1992 stationwagon whos fuel gauge worked just fine and after putting that working fuel pump assembly into my car, the problem still persists. The fuel gauge is still on Empty. I use the odometer to let me know when to fill up, but I'd like to have the "LOW FUEL" light to be off.

[mightymoose_22]

THe sending unit for the gauge is on the top of the fuel tank which is accessed by removing the rear seat cushion. It could also be a faulty gauge... but I can't say that I have ever found a faulty gauge :P

Anyway... you probably need to replace the sending unit.... but removing it and cleaning it up may work too!

[KimMG]

It is possible the float for the sending unit has a leak and is full of fuel.

[12Ounce]

Some older Escorts had a small "instrument voltage regulator" that was mounted on the instrument cluster printed circuit. Easy enough to replace once you have the instrument cluster removed.

I don't don't what year, or if, this device was eliminated.

I would first check to make sure the harness back to the tank is working. Try hooking up the removed sender/pump unit outside the tank and move the float around for a check.

[Paul78zephyr]

Originally Posted by 12Ounce

Some older Escorts had a small "instrument voltage regulator" that was mounted on the instrument cluster printed circuit. Easy enough to replace once you have the instrument cluster removed.

I don't don't what year, or if, this device was eliminated.

I would first check to make sure the harness back to the tank is working. Try hooking up the removed sender/pump unit outside the tank and move the float around for a check.

His car has an IVR (even the newer models use one but they are better designed and more integrated into the overall instrument cluster circuit) and I believe if the IVR was defective the temp gauge would be off too and he did not mention that. It could either be a bad sender or bad gauge, or even a bad ground somewhere. You can easily rule out the sender without removing it (its a PITA to remove as its integral to the fuel pump and the entire assembly must be pulled up from the tank). Essentially the fuel sender is a variable resistor - one resistance when full which changes incrementally to another resistance when emply. You simply need to put an ohmeter across the sender terminals with the tank full and then again with the tank less full and see if there is any difference. I do not have the specs on the sender resistances but I will look and if I find them I will post them.

Paul

[kerker]

I would first like to thank everyone for thier responces and guess I need to make some updates. First the TEMP gauge works just fine. And all the other gauges work just fine (speedometer, tachometer, idiot lights). Since I did put on a different fuel pump assembly, I would like to rule out that option. I also did remove the original and second assembly and moved the float while the car was on and had no difference in the meter. Checked all the fuses on the driver side and under the hood, if there are more somewhere else then I would love to know where they are.

So lets assume that the wiring is fine at the pump, the plug is just fine and all the fuses work. I even jiggled the fuel pump plug while the car was running and the harness around it and there was no change. I haven't gone so far as to put a volt meter to it yet, just trying the simple stuff first and hoping that someone else has had the same problem and fixed it.

With that in mind, any other options?

[mightymoose_22]

Use an ohmmeter.
Since you already have the float assembly accessible, test the signal coming from it with the ohmmeter. If the resistance does not fluctuate... something is wrong with the sending unit.
If it does work, test the signal at the gauge... if the signal is still there, your gauge is not registering it... change the gauge.

I find it incredibly rare that a gauge goes bad... but I suppose it does happen sometimes.