!986 Fuel Tank Sending unit
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From: St. Louis, Misssouri
!986 Fuel Tank Sending unit
I am working on my boy's 1986 Ford F-250. The gas gauge does not work. We removed the tank and I found a 2 lead sending unit plug. I check the resistence on the sending unit and found about 3.5 ohms. So I know the sending unit works. I grounded one post (yellow I think) and the gauge went to full, so the gauge circuit is good. Finding this, I made a tank ground out of a short piece of 14 gauge wire, drilled holes in the flange of the tank next to the welded seam and the body that I grounded it to to test it. Everything has been cleaned and I have good connections on my terminals, but the gauge stll doesn't work. Is the other wire (black) some sort of ground for the sending unit? If so, can I just jumper that black wire to my new ground that I made?
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Joined: Nov 2007
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From: Denver Metro Area, CO
I forget what the exact range is, but 3.5 ohms seems awfully low to me, I would check it
over the range of travel of the float.
In my experience, the major culprit is the, um, wiper-thing inside the tank.
If you remove
the sending unit and remove the triangular-shaped cover, you'll see what is basically a
rheostat (variable resistor) and there's a brass contact that swipes across a piece of
material with a VERY fine wire wrapped around it. That wire eventually wears through and
breaks, I've seen lengths of that wire floating around *****-nilly inside the cover.
Another possibility is the float has gotten a hole in it and stays at the bottom.
Yes, I believe the black wire is ground (somebody will correct me if I'm wrong), but I for
some reason doubt that's your problem.
over the range of travel of the float.
In my experience, the major culprit is the, um, wiper-thing inside the tank.
If you removethe sending unit and remove the triangular-shaped cover, you'll see what is basically a
rheostat (variable resistor) and there's a brass contact that swipes across a piece of
material with a VERY fine wire wrapped around it. That wire eventually wears through and
breaks, I've seen lengths of that wire floating around *****-nilly inside the cover.
Another possibility is the float has gotten a hole in it and stays at the bottom.
Yes, I believe the black wire is ground (somebody will correct me if I'm wrong), but I for
some reason doubt that's your problem.
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Joined: Jan 2001
Posts: 56,984
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From: Virginia
Yes, take another ohm reading on the sending unit with it out of the tank. Put your meter on one terminal, and the other on the frame of the unit. Sweep the arm up and down and your meter should go from I believe approx 10-90 ohms.
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