gas guage ?
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Senior User
Joined: Jan 2004
Posts: 186
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From: river ridge,La
gas guage ?
my gas guage has quit working properly.it doesn't register over a quarter of a tank , no matter how full it is.what is the most likely culprit for this problem..........wayne
Laughing Gas
Joined: Jun 2003
Posts: 1,218
Likes: 2
From: Parkville, MO (KC)
Sunk float. Test the wiring first by pulling the lead off the sender unit on top of tank. Ground that lead (orange if my memory serves me correct). Guage should go to Full. If it does not, then there is a different problem, but I'd guess that your problem is the sender or the float is half sunk.
Once you have isolated the problem to the sender, then you can take the sender out. See if the float is leaky. If no, you can test the sender by grounding it (use a piece of temporary wire) and vary the sender position. See what your guage does. Alternatively, you can hook it up to an Ohmmeter. As I recall the resistance is like 25-150 and varies with position of the arm. Don't quite me on those numbers. But a shot sender will have much higher resistance #'s.
If it turns out that my first diagnosis is correct, then you need a new float. Several places that do old ford parts have them. Maybe even the large chains can get them -- was used till 71, so ask the parts monkey for a fuel sender float for a 70, as you will have better luck with newer year truck. Some guys say you can solder a hole in a float. They are like $5 -- for that I would not bother trying to solder.
Finally, DO NOT RTV THE GASKET around the sender. Re-use the old one, or make a new one from cork. RTV in the gas tank is a real pain to get back out, especially if it gums up on the screen at the bottom of the lead pipe.
Once you have isolated the problem to the sender, then you can take the sender out. See if the float is leaky. If no, you can test the sender by grounding it (use a piece of temporary wire) and vary the sender position. See what your guage does. Alternatively, you can hook it up to an Ohmmeter. As I recall the resistance is like 25-150 and varies with position of the arm. Don't quite me on those numbers. But a shot sender will have much higher resistance #'s.
If it turns out that my first diagnosis is correct, then you need a new float. Several places that do old ford parts have them. Maybe even the large chains can get them -- was used till 71, so ask the parts monkey for a fuel sender float for a 70, as you will have better luck with newer year truck. Some guys say you can solder a hole in a float. They are like $5 -- for that I would not bother trying to solder.
Finally, DO NOT RTV THE GASKET around the sender. Re-use the old one, or make a new one from cork. RTV in the gas tank is a real pain to get back out, especially if it gums up on the screen at the bottom of the lead pipe.
Fleet Owner
Joined: Oct 2004
Posts: 20,778
Likes: 225
From: Newton America :-P
I agree with CDHerman. Its either the float (most likely) or the unit... both are cheap to replace. The tank doesn't HAVE to be empty, but when you remove the float you will most likely drip gas all over (even if you are carful) The whole unit unbolts/unscrews right out of the top.
