91 CP fuel gauge reads full all the time

[1990LTD]

Usually it will stay where it was, and slowly drop back down, so if I'm out of the car a while, it'll be down at the E. If I get back in a few minutes after powering off, it'll be just barely lower.

[86VickyLX]

If my gauge doesn't drop to E when it's got no power, what do you figure that indicates? Sometimes it will read around 1/2 tank (when on) when it has much more or much less fuel in it, then if I tap it a couple of times it usually goes to where it's supposed to. Only started happening when it started getting really cold out.

That sounds like the gauge is sticking



tbirdbrian, if the gauge reads full even with the sender disconnected, then it sounds like the two wires are shorted together. If you have an ohm meter or a continuity checker, connect it to the prongs of the plug, if you get a lit light or little resistance, the wires are shorted together somewhere. If there is no shorts, then you're probably looking at getting another fuel gauge.

[91waggin]

tbirdbrian, if the gauge reads full even with the sender disconnected, then it sounds like the two wires are shorted together. If you have an ohm meter or a continuity checker, connect it to the prongs of the plug, if you get a lit light or little resistance, the wires are shorted together somewhere. If there is no shorts, then you're probably looking at getting another fuel gauge.

Um no.

You've got it backwards. If the two wires were shorted together, the fuel gauge would read empty, not full. On these sending units, the resistance is low (closer to a dead short) when the tank is empty, and high (further from a dead short) when the tank is full. Review the wiring diagram I posted earlier.

Therefore, the two wires shorted together are obviously not the problem. If they were shorted together, the tank would be stuck at empty with the low fuel light on, rather than stuck at full.

If you want to check the gauge without removing the sender, get a couple of resistors from radio shack. Get a 160 ohm resistor, get a 15 ohm resistor, and get a couple in between. When you put the 160 ohm resistor between the two prongs of the plug, the gauge should read full. When you put the 15 ohm resistor between the prongs on the plug, the gauge should read empty. When you put the other resistors in, the gauge should be somewhere in the middle.

Alternately, you can pull the sending unit, hook it up, and run the float up and down to check the gauge.

[Glen]

Mine will stay on E, with the low fuel light on, in the winter when it is cold and work in the summer. It has done the for the past 2 years. I just fill it every 150 to 200 miles. The light doesn't come on for about 10 sec. after I start the car, the needle never moves.

[tbirdbrian]

91 CP fuel gauge fixed.

Well, the fuel gauge on Connie is working again. It was a very high tech solution that I thought I should pass on.

We got a butt load of snow recently and there were many snow plow drifts at the bottom of driveways. I backed into and through one of these big snowdrifts (not on purpose ) leaving my buddy's driveway the other day. Gotta love the Trac-Lok in a wagon. Anyway, since then my fuel gauge has been working perfectly.

So, my advice to you all the other Panther owners with fuel gauge problems is to drive through some snow drifts. I can't find confirmation of my solution in any tech pubs, but it worked for me.

Thanks for all the advice!
-Brian

[1990LTD]

It's good for your skin, too!

[91waggin]

the float gets sticky. This happens to me from time to time, and then I drive over some bumps and after about 80 miles it starts working again. Just remember to reset your trip every time you fill up, just in case it decides not to work again.