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Old 12-25-2011, 01:37 PM   #1 (permalink)
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Default fuel guage only reads half a tank

Ive checked all the wires and they work. When I fill up it only goes to half a tank on the gauge. It will lower as I use gas but only shows 1/2 when its full. Ive read other post and from what I can tell it seems like the sending unit is bad. Any other thoughts or ideas? MERRY CHRISTMAS
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[COLOR=Red][FONT=Arial Black]1968 289 Coupe
60k miles #'s matching Restored

1966 Resto mod with 5.0 and t-5 trans with ford 9" rear

1966 couple with the granny inline 6
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Old 12-25-2011, 02:50 PM   #2 (permalink)
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I am betting your float (in the tank) has a pinhole and is 1/2 full of gas. If you change the sending unit- run that car as low as possible on fuel prior to changing it. Extinguish all flames, pilot lights, etc prior to removal. You don't want to know what 5 gals of gas feels like running down your arm, and you really don't want to lay in a large puddle of gas knowing you have to finish the job; while nervously eyeing a trouble light, etc
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Old 12-25-2011, 03:05 PM   #3 (permalink)
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Yep, mine started reading about half full then went to empty. My fuel sending float had a small crack in it and filled with gas. I replaced the brass float (cost $3) put in a new gasket and pick up filter and all is well again.
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Old 12-25-2011, 04:55 PM   #4 (permalink)
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If gauge reads full when grounding the sender wire at tank, then it has to be the sender. Even new, if not bent properly it won't read correctly.
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Old 12-25-2011, 06:34 PM   #5 (permalink)
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Soon it will read empty all the time. You will need to remove the gas and replace the sending unit.
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Old 12-25-2011, 07:37 PM   #6 (permalink)
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I did ground it out and it reads full, So it must be the sending unit. Thanks for the info guys and Merry Christmas
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[COLOR=Red][FONT=Arial Black]1968 289 Coupe
60k miles #'s matching Restored

1966 Resto mod with 5.0 and t-5 trans with ford 9" rear

1966 couple with the granny inline 6
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Old 12-25-2011, 07:59 PM   #7 (permalink)
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I had a similar problem with my '66 even after replacing my sending unit. The wiring appeared to be in good shape and the gauge seemed to work (from half full to empty)...just as you described yours. I found that the factory gauges (atleast for 1966) can be adjusted for accuracy. I'm not sure about your car, but it may be something to watch for. My first thought would be a bad sending unit/float though.
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Old 12-25-2011, 09:38 PM   #8 (permalink)
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Just went thru this. Even thro ~ 5 yrs ago I installed a NOS sending unit to avoid issues, although was fine for that time. My gauge starting on ocaasion thr-out summer reading maybe half full. I did the ground the gauge wire and all. So I yanked out sending unit and found my brass float half full of fuel. While at it ordered new flaot & tank filter/screen from Virginia Mustang. Installed and put 4 gal in, read 1/4 tank, added 4 more read 1/2 tank. All fixed.
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