Cormac
New member
I have a Ford 6600 tractor and have never seen the fuel gauge needle. How do I start my diagnosis to figure where the problem is? Thanks
Fuel gauge
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v8dave
Platinum Member
Need a little more information.
You can't see any needle in the gauge? Like it has fallen off?
The needle is stuck beyond either full or empty?
The needle shows someplace but it never moves?
You can't see any needle in the gauge? Like it has fallen off?
The needle is stuck beyond either full or empty?
The needle shows someplace but it never moves?
It is a left to right gauge not circular (like a clock) so the needle could be there. It may just be too far to the left or right (and out of sight). I am assuming that there is an electrical issue and the gauge. I am looking info that I can test and determine if it is the sending unit or gauge.
Glenn9643
Veteran Member
It requires electricity for most to work. Do you have a multimeter? It may be as simple as a broken circuit.
It may be the sending unit at the tank?
It may be the guage itself?
Rule these out one after the other and you should be able to correct it.
It may be the sending unit at the tank?
It may be the guage itself?
Rule these out one after the other and you should be able to correct it.
v8dave
Platinum Member
First test to that there is battery voltage on one side or the other of the two terminals on the back of the gauge. If not, you have an open fuse or bad wiring. You will find voltage on both sides of the gauge if the systems is all working ok. The voltage on the wire that goes to the tank sending unit will vary depending on the fuel level in the tank--in a normally operating system.
If you have voltage on one side of the gauge and none on the other, disconnect the side with no voltage. Check to see if this wire is shorted to ground. Or disconnect both ends of this wire (the other end should go to the tank's sending unit) and replace with temporary jumper. If it works, replace the wire, it's shorted to ground.
If you have battery voltage on one side, then the other wire on the other side goes to the tank sensor. A very quick tap of this wire to ground will cause the gauge to swing to full. Be careful, just a quick tap while looking at the gauge. If it doesn't move you have a bad gauge. Repeat this step at the sending unit to verify the wiring on this side too. If the gauge moves in both cases then you have a bad sending unit.
If the guage moves in the first case and not in the second, the wiring is bad-it's broken open. Just to be sure, use a clip lead to bypass the wiring from the guage to the sending unit.
If the gauge moved in the previous steps and you still have no indication, the sending unit needs replacement.
If you have voltage on one side of the gauge and none on the other, disconnect the side with no voltage. Check to see if this wire is shorted to ground. Or disconnect both ends of this wire (the other end should go to the tank's sending unit) and replace with temporary jumper. If it works, replace the wire, it's shorted to ground.
If you have battery voltage on one side, then the other wire on the other side goes to the tank sensor. A very quick tap of this wire to ground will cause the gauge to swing to full. Be careful, just a quick tap while looking at the gauge. If it doesn't move you have a bad gauge. Repeat this step at the sending unit to verify the wiring on this side too. If the gauge moves in both cases then you have a bad sending unit.
If the guage moves in the first case and not in the second, the wiring is bad-it's broken open. Just to be sure, use a clip lead to bypass the wiring from the guage to the sending unit.
If the gauge moved in the previous steps and you still have no indication, the sending unit needs replacement.