Fuel Gauge
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Joined: Jan 2004
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From: Spokane, WA
Fuel Gauge
I've a 1970 F250 with gauges. The problem is I can't seem to get the fuel gauge to read full when the tank is. I grounded the gauge and the needle swings past the full mark. I replaced the IVR and no difference. I checked the sender and found it to be out of specs and the float full of fuel. I replaced it with a new Ford unit and checked the new unit with an ohm meter to be sure it was within spec. Still no difference. Tank reads just above 3/4 when full. When I first start the truck the needle will swing to full and then I can see the IVR pulsate the needle and it slowly drops back to just over 3/4. My thinking is that the wiring might have built up resistance in it or that my grounding wire(s) may need to be cleaned up. Will I need to clean up all the grounding connections or just the one for the fuel system? Has anyone else solved this kind of problem? As always thanks in advance for all replies.
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From: Virginia
"My thinking is that the wiring might have built up resistance in it or that my grounding wire(s) may need to be cleaned up. "
You are right on with that statement. What I would do is take the wire off at the sending unit, and find a good clean ground on the frame and ground it just like you did at the guage. If the guage reads full, then you know your wire is good to the guage. If it gives you the 3/4 reading, I think I would run a wire to the battery negative and touch the sending unit wire to that. If you only get a full reading on the negative of the battery, then you must have a ground strap somewhere that is not grounding the frame properly. If you still get a 3/4 reading on the bat neg, then there must be a problem with the sending unit wire going to the tank.
If the frame ground gives a full reading, then take the wire and ground it to the tank ground. If the 3/4 problem comes back, then you know your fuel tank does not have a good ground.
You are right on with that statement. What I would do is take the wire off at the sending unit, and find a good clean ground on the frame and ground it just like you did at the guage. If the guage reads full, then you know your wire is good to the guage. If it gives you the 3/4 reading, I think I would run a wire to the battery negative and touch the sending unit wire to that. If you only get a full reading on the negative of the battery, then you must have a ground strap somewhere that is not grounding the frame properly. If you still get a 3/4 reading on the bat neg, then there must be a problem with the sending unit wire going to the tank.
If the frame ground gives a full reading, then take the wire and ground it to the tank ground. If the 3/4 problem comes back, then you know your fuel tank does not have a good ground.
