projectresto83

How can you tell if the fuel gauge works properly or if the sending unit is the problem. After swaping to an efi tank in my 83 years back the level gauge hasn't worked right. At first I thoughtthe wires werewas just backwards on the unit so I tried swapping them and it still reads backwards for when there is fuel in it and it reads full (empty on the gauge) after about 5-7 gallons or so.

Either that or are the sending units for the 4 eyed stangs have a different reading then the efied cars and it won't work correctly with the older gauge?

projectresto83

I have seen that the sending units are different so I am guessing that the resistance's are different.
Somebody stop me if I am wrong but the carb sending unit mounts in the top on the hump where the pump and pickup on the efi are supposed to be right? Then where the sending unit is on an efi thank there isn't anything right.

Still, how would you tell that the gauge works right if the sending unit doesn't?

98gt_runner

I have the same problem with my 87gt. gauge reads full on empty tank. the sending unit is located inside the tank, i changed mine for $71 but didnt cure the problem. Im still looking for answer.next move is to check for grounding

projectresto83

Try a new gauge and see if that works. I am using an efi sending unit in a four eye so I think that is my problem. Mine doesn't work at all now so there isn't any more guessing. I just watch my milage and fill up at around 150 miles or so.

mjr46

you need the correct sending unit..resistance is calbrated different..if you have an efi tank and try to use the 85 and below style pick up tube/sender assembley then you'll have to remove the baffle in the take that surrounded the efi pump assembley as a carbed mustang tank had no baffle whatsoever

projectresto83

That is what I figured I would have to do along with most of the EFI's unit and just leave the top to seal the hole. That is why I asked the question at the beginning of the thread. I forgot I even started this one.

Joel5.0

The following is the "bench test" procedure using resistors for either type of fuel gauge..... bimetal or magnetic sender.

projectresto83

Cool. If you ground out the lead it also reads full. Like testing a coolant gauge.