Help!!! Recently bought 87 Transam with some wiring problems.Gauges didn't work instrument lights didn't work.Got all that going but gas gauge still shows full even when its not. Any ideas what it could be.
Thanks for the help

 

hey man! it could be the sending unit in the famous gas tank! thats what i think anyways g-luk

 

I agree, it's either someone replaced something on the sending unit, ie the fuel pump, and messed up the wires or the fuel quantity level, or the wires in between the sending unit and gauge are f-ed

 

makes sense to me too.

 

I REALLY hope this is not the problem, but: On my 92 RS, there's a plastic baffle inside the tank to keep the fuel from sloshing during cornering. I replaced my fuel pump, but got the fuel level float in the wrong position in relation to the baffle. Result: the fuel gauge showed full all of the time. Cure: I had to take the tank down a second time and correctly reposition the float. Point: If someone did remove the fuel pump for any reason, they could have easily hung up the float as I did. But, since removing the tank is such a pain, I hope this is NOT the problem with your gauge. Best of Luck!

 

Thanks for the info. Looked under car see if sending unit is easy to get to.Didn't see it. Oh my *** is the gas tank that hard to get out.New to this game but willing to learn. Feel like sharing your expertise.
Thanks for the help!!!

 

you'll have to drop the exhaust and rear axle to get the tank out

 

fuel pump and sender are on top of the tank...its such a pain to get to, many people just cut a hole in the floor of the trunk to get to it.

 

Ilike that idea no way in hll was I going to go at it from underneath. Thanks all of ya'll for the input. I'm sure i will be asking for help on the next project.

 

DO NOT cut a hole in your car to get to the sending unit. it is unsafe and the car really dont need a hole in it about 2'x2'. If you pull the carpet back from inside the hatch you will notice that the metal is stamped with groves in it. this is there to help strengthen the cars chassis to a point . plus once your done, you will need to weld the hole back and welding sparks dont mix well with interior fabric and gas vapors. Do the job the RIGHT way and drop the tank from below.

 

you gotta drop the axle???? f**k that.. id cut a hole in the car i dotn care what anyone else says.....

 

To be completely honest, taking the tank out is alot of work. But, once you cut the car, it will never be the same. Besides, there are serious safety issues in cutting around the fuel tank! It's really not too bad to take the tank loose, in terms of the complexity of the work. It just takes a while. You have to take the panhard bar, shocks, and antisway bar loose. Then the springs will fall out and the rear end will drop far enough to let the rear end down. You don't actually have to take the rear end out. You don't have to disconnect the driveshaft, trailing arms, etc. You should also be able to pull your exhuast far enought to one side to not have to cut it off. Really, the worst part is maneuvering the tank to get the filler neck out of its pocket. But having done this twice, I can say you will probably be much happier if you do it this way, than if you cut the body. A month from now, the extra time you spent won't matter much.

 

i dont have the money to buy the tools to do such work.. seriously man. i have myself a nice lil 12 dollar jack from k-mart that gets me through what i usually do. thas nuts , takin out half the back end. besides its all cold here. id rather pay a company for it.

 

I would venture a guess that you have a defective gage and not the sending unit. That was my problem and replaced the gage and problem solved.

 

The easiest test would be to check the purple (or whatever color aside from grey, fuel pump + wire, or black, ground) at the harness plug in front of the gas tank for an ohm rating of anything between 0-90, 90 being a full tank. If you know your tank is at least half full, the ohm rating on the sender wire should be somewere around 45 ohms. If you can't get a reading there, then your sender is definatly cooked. If you get an ohm reading at the back harness connector, there is a break in the circuit before that or, as stated, you may have a bad gauge.

A pegged full reading though means there is an open circuit, pegged empty is 0 ohm or the circuit is grounded out.