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...on the wife's Excursion. Several years back I installed a new tank pickup tube and/or sending unit from NAPA that does not have the dreaded sock filters. About a year or so ago the fuel gauge needle decides to sit at F when the truck is on, and when the truck is off the needle goes back to E. I have tried disconnecting the batteries, running down bumpy roads, banging on the tank etc. with no luck. We have been running according to the odometer and dropping fuel accordingly.
So yesterday I did some EBP sensor replacement and tube cleaning maintenance and decided to hook up the laptop to check readings. In going through the Forscan PID's I noticed there were two that had to do with fuel readings...one was a % value and the other was a voltage value. So with the key on and engine off the voltage was at 5 and the percentage was around 33% which is not correct given I filled it up yesterday and drove it a couple miles home. Now with the engine running I still get a voltage of 5, but the percentage goes to 99% which is correct. I think Forscan is reading these values via the PCM. I know the gauge reads 5 volts which should be full. Is this a ground problem, and if so where is that ground?
Ford's fuel gauge use the resistance of the float level resistor to show tank level. The resistance would lessen as tank approached empty. You should be able to disconnect the wires going to the fuel tank sending unit and the level will read full. If you short between the fuel level wires, it should read empty.
These are the schematics from a 2014 and assume they are similar to yours. The wire colors might be different.
Ford's fuel gauge use the resistance of the float level resistor to show tank level. The resistance would lessen as tank approached empty. You should be able to disconnect the wires going to the fuel tank sending unit and the level will read full. If you short between the fuel level wires, it should read empty.
These are the schematics from a 2014 and assume they are similar to yours. The wire colors might be different.
DIESEL
So with mine being a diesel Excursion it should have a yellow and green wire, which I will verify that with the old sender pickup unit I think is still laying around. I read through another thread where a very similar situation was happening and it was suggested to put the gauge cluster into self test mode, but I don't think that's possible with a 2000 style cluster. Anyway, they had a DTC showing a short to ground and asked where the sender was grounded, but nobody answered the ending. That's why I asked where the sender was grounded. It looks like it might be the green wire might ground to the side of the sender inside the tank and the yellow wire just reads 0v-5v resistance?
