Location of ground wire from fuel sending unit on ford f250

The sending unit is grounded through the flange that you bolt to the tank. That same flange (for the sending unit) also served as the tank ground on a poly tank. If it were mine I would run a separate ground wire from the tank sending unit flange to a known good ground point (not the frame).

Not exactly sure when you say "in gas tank". There are 2 seperate grounds for the fuel pump/sending unit inside the fuel tank. The ground for the fuel pump is located under the left hand (drivers) side of the instrument panel behind the kick panel. The ground for the sending unit is located on the left hand (drivers) side of the engine compartment near the radiator. Sorry I don't have any pictures and I hope this helps....

My parts book shows a speed sensor in the side of the transmission where the cable used to be.

I would start by accessing the wires going to the fuel tank check both ground as well as resistor wires going to the fuel tank if these are ok its probably the fuel sending unit located inside the fuel tank

check wire to fuel pump assy in tank. Likely corroded connector there or a bad sending unit in tank.

When you ground the sending unit wire gauge will go to full you have a short to ground on this circuit yellow and white wire from the tank to the gauge or the sender is shorted out

the sending unit could not have power or the fuse could be burnt out. Sometimes the sending unit does get stuck.

Ford has lots of problems with the sender reliability. Typically, the sender (and expensive fuel pump) replacement resolves the issue. To test, you need to take the connection off of the sending unit, at the tank, turn on ignition, and then ground and un ground it and view results at the gauge. If the gauge responds, the sender needs to be replaced.

There are aftermarket senders that cost less than OEM.

You will need to locate the wire to the fuel sending unit at the fuel tank.

Once you locate the wire, disconnect it and see if the guage goes to 'E". If the guage goes to "E", you probably have a bad sending unit.

To double check, ground the same wire to clean metal on the frame with the key in the "on" position (not running). If the guage does not move, the guage is bad. If the guage moves from E to F, the sending unit needs to be replaced.

I JUST SPENT A WEEKEND SOLVING THE ISSUES THAT SEEM TO BE THE SAME AS YOURS. FIRST THE PROCESS OF THIS MODEL IS THAT WHEN THE KEY IS PUT IN THE RUN POSITION, THE FUEL PUMPS ACTIVATE AND ONLY FILL UP THEMSELVES. WHEN THE TRUCK ENGINE IS CRANKED, THE OIL PRESSURE ACTIVATES THE SENDING UNIT AND IT ACTUALLY TELLS THE FUEL PUMPS TO KEEP PUMPING WHILE THE ENGINE KEEPS TURNING OR RUNNING. IT IS A SAFETY ISSUE, AS IN A WRECK, THE ENGINE DIES, AND THEREFORE THE FUEL TO THE ENGINE IS STOPPED, AS A FIX, TRY PRIMING THE CARB, AND SEE IF IT RUNS BRIEFLY. YOU WILL ELIMINATE ALOT OF EXTERRANEOUS ELECTRICAL ISSUES IF IT RUNS. NEXT, CHECK CONTINUITY AT THE FUEL PUMP RELAY. IT IS LOCATED UNDER A PLASTIC COVER ON THE FIREWALL TO THE RIGHT OF THE BRAKE BOOSTER PUMP. MINE HAS 5 WIRES GOING TO IT. I HAD TO UNSCREW THE COVER TO ACCESS THE HIDDEN SNAP THAT HOLDS IT IN PLACE. HAVE SOMEONE CRANK THE ENGINE AND FEEL IF THE RELAY ENERGIZES. IF IT DOESN'T, AND THIS IS WHAT WAS WRONG WITH MINE, YOU WILL NEED TO FIND AND REPLACE THE OIL PRESSURE SENDING UNIT WITH 2 WIRES. THERE ARE 2 WIRES THAT WILL LEAD YOU TO THE OIL PRESSURE SENDING UNIT FROM THE RELAY. THERE ARE 2 SENDING UNITS AND THEY ARE LOCATED AT THE REAR OF THE EXHAUST MANIFOLD, BEHIND THE CARB. THERE IS A BIG ONE, WITH ONE WIRE, WHICH IS THE OIL PRESSURE SENDING UNIT FOR THE GUAGES, BUT BELOW THAT IS ANOTHER SMALLER SENDING UNIT THAT HAS 2 WIRES GOING TO IT. IT CLOSES WHEN THE ENGINE TURNS OVER AND ACTUALLY TELLS THE FUEL PUMPS TO KEEP PUMPING GAS. SEE IF THIS WORKS. THE FUEL PUMP RELAY WAS 15 DOLLARS AND THE OIL SENDING UNIT WAS 16. SPENDING ALL WEEKEND WITH THE WIRING SCHEMATICS AND TRACING ALL OF THAT STUFF-----------PRICELESS.