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Discussion Starter #1
HI ALL
Well to start off I took the orginal tank out because it was under the doors on the pasanger side of the truck (truck in signature , and I didn't like it there). So I put in a behind the seat tank from a 72 F-100 in the bed up agianst the front of the bed. When I fill it up it goes way past the F mark, then takes a long time to move, once it starts to move it seam to go very fast (you can all most see it move). Then it well start to fluctuate. Like it well be at 1/4 when you shut it off then when you start it backup it well go like to 1/2 or a little past and contenu there and move regularly. There seams to be not a set fluctuation as it is different each time. So I carry a 2gal can in the back just in case..
Any answers anyone??
"Gound not good enouff ?? maybe??"
tim
 

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if all you changed was the tank location and the gauge worked before, it sounds like a grounding problem. you could run a ground wire from the tank to the gauge, or just ground it to the frame. Gas gauges are picky about a good ground.
 

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I'd guess the sending unit/float that came with your newly acquired tank has some bad spots on it. You could get another one at a scrapyard but there's a good chance it'll be worn out too... you might want to look into getting a new one.
 

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Take a multimeter you your old sending unit. Read the ohms at full, half, and empty. Then do the same with your new tanks sending unit. The should read the same, or at least very close. If they are different that is your problem, they were made for sending units with different ranges.

Also try slowly swinging the arm from full to empty, the resistance should change smoothly with your movement, and there should be no spots where it spikes or dips.
 

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Discussion Starter #5
THANKS for the input.
The tank is a total different animal the orginal was the 64 international side tank and the one in it now is out of a 72 F-100. So the ohms may be my probs. But you would think it would be constent , ( Well it kind of is) I think I'll run a ground wire and see if that cures it. Then may be when I finely put in the Temp and oil gages in the dash I'll add a new gas gage (after market for ford).
Thanks again

Tim
 

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It won't be anywhere near the same... if you look at aftermarket fuel gauges, Ford uses a sender that reads empty/full 73/10 ohms... while others are 240/33, 0/30 (opposite direction), 0/90, etc... they didn't standardize on it at ALL. You'll either have to retrofit a international sender into your new tank, or buy an aftermarket fuel gauge made for a Ford sender. From what you describe, with it staying full for a long time and then dropping quickly to 1/4 and then staying there, I'd bet your gauge is probably made for the 240/33 range, while your Ford tank is 73/10. If this is the case, you could make it a LITTLE more accurate by buying a 20 or 25 ohm ceramic resistor from Radio Shack and putting that in-line with your sender wire... that would move it to a 93/30 range, which means it would read close at full tank, but still bottom out at about 1/4 tank.
 
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