Mustangrules

Fuel gauge reading only 1/2 tank when actually full ! I believe there are 2 x sender units either side under back seat , does anyone know if they work together and take an average reading or if one goes from empty to 1/2 and the other from 1/2 to full and which does what ? I have bought 1 new sender unit but not sure which one to replace or even if I need to replace both .
appreciate any help ! Just in case anyone thinks it could be the FPCM I have already replaced with a new one and it made no difference.

Bert

are you sure it's really full? how much gas is it taking when you fill up?

Mustangrules

Yes , full to the brim Definitely ! and only reading 1/2

Mustangrules

Also ,forgot to mention when driving my gauge was showing 1/4 tank it suddenly jumped up to 3/4 which I know is not right ! so I stopped and filled up cost me roughly $90 but when I turned on the car it now only shows 1/2 tank.

shaneyusa

Could it have anything to do with the electrical issues you are having with the rear lights? Sounds like there was quite a bit of rewiring done to make it legal for over there, maybe something affected the power to the tank sending unit? If not may be a bad guage or the tank unit.

Mustangrules

Not 100% sure but I think it may have been a coincidence ! All the wiring has now been sorted and all works as it should , so I just need to sort out the fuel gauge problem and yes you may have a point about the gauge itself but given that it fluctuates and is registering it sounds more like a sender issue . Just not sure if both are playing up or just 1 ? The other annoying problem is that Ford in their wise wisdom decided to put the bigger locking rings for the sender and pump but the access hole is about 12mm smaller so you can’t get them out without dropping the tank or cutting out bigger holes like the 2015 models have . I don’t mind taking it to a Main dealer but they will not cut out the holes , which would be the easiest way out for now and any problems in the future !