mustangman101

Ok, the car is a 91 SSP 5.0 coupe with and auto. I have changed the sending unit with a known working unit. Nothing changed still reads on E. tried a different cluster and different ANTI-SLOSH mod. Still no change. I know the guage works cause when i unplug the anti slosh module the guage pegs past full. I tried unplugging the harness at the sending unit, the guage stayed on E, when i know it should have read full. is there a ground that could be ungrounded somewhere in the harness behind the cluster?

Every other guage is fine except the fuel guage. the cluster doesnt look burnt or anything.

I am running out of idea's as to what else it could be. i even changed the wiring harness going to the sending unit with no luck. anyone know anything else i could do that i havent tried?

Thanks

blacksheep-1

A better way to check it would be to operate the float arm slowly and see what the gauge does, the way you're doing it can lead you in the wrong direction. Make sure the gauge is grounded, most issues that I have come across with regarding sender units are ground related. I ran into a Ranger once where the float arm would hang up in the internal wiring harness. Check all the connections to the gauge with a test light or voltmeter, once that is done, check the sending unit then work your way back up to the gauge cluster.
You can unplug the sender and check the unit itself with a ohm meter, operate the lever, watch the meter.

mustangman101

Forgive my ignorance, but what setting on a multi meter would be for ohms? I don't know much about electrical things with these cars

blacksheep-1

Ohms won't measure current, it only measures resistance, so you can only use it on the sending unit AFTER it's disconnected from the car's electrical system. The "ohm" meter feature, which is on most multi meters looks like a sideways figure 8. Basically, hold one side of the meter to the unit's body, then connect the other lead to the negative terminal on the sending unit (it may be positive, it's been awhile, just check both, since there is no current, it won't hurt anything. if you "miss"). What you are looking for, at the sending unit, is for the meter to move up and down the gauge as you move the float lever. If that happens then the sending unit is OK, your problem is somewhere else besides the sending unit.

mustangman101

Ok, well the multi meter I have doesn't have that feature. I did make a little progress. I read online about people fixing their anti slosh module with a part from radio shack. Its the big red capacitor on the top. It cost 1.50 for a new one. Bought it (the new one is blue 35v 100 farad for anyone who wants to try this cheap and possible easy fix for their broken fuel gauge before dropping the tank like I did) and sodered¿ it on.
When the anti slosh module is working correctly, if you unplug the harness at the sending unit. The fuel gauge will peg past full, telling you the sending unit is bad.

I unplugged that plug before I changed the sending unit the first time and the gauge never moved, so I know that 1.50 part fixed the anti slosh module. Going to buy a new sending unit as I now know that is the only thing left.

Thanks for the info