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Old 08-05-2021, 04:38 AM
Brian Baker's Avatar
Brian Baker Brian Baker is offline
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Default Fuel gauge always reads full

The issue has crept up slowly on my Can Am in the last 15 years or so. It started out as reading full until it got to about 1/2 tank and then the needle would begin moving toward empty, but never going past the 1/2 tank mark on the gauge (that is to say I never let it go past 1/2 before filling it up, and it always took 18-20 gallons). Now it seems the needle doesn't move at all. It's pegged at full.

Is this a faulty ground, or a faulty sending unit? I plan on dropping the tank soon for inspection (and replacing of rubber hoses from tank to hard lines).

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Old 08-05-2021, 07:30 AM
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If the sender is similar to my Firebird's, the gauge pegs full when it doesn't get an input from the sender. I found that the main sender connector was dirty and not making a complete connection all the time, so my gauge would peg full intermittently (and it happened more often over time). I actually soldered the connection solid on the bottom side of the sender (after all gas had evaporated, of course). Now the gauge reads low because I tried bending the float arm to make the gauge more accurate when I got the car. A coated strap from the resistor connects at the bottom through a toothed washer; you'll see how it works when you get the sender out. Just use your ohm meter to see when you have a good connection between the top of the sender and the resistor.

Mine seems to be the original sender, by the way. I'll keep using it as long as I can, because I have a reproduction on hand, but the hard line is too long and runs into the exhaust pipe...nothing like modifying a new part.

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  #3  
Old 08-05-2021, 07:33 AM
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The sender is grounded to the body. Check for good connections at both ends. Agree with Aaron's suggestion also.



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  #4  
Old 08-09-2021, 09:42 PM
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Quote:
Originally Posted by Brian Baker View Post
The issue has crept up slowly on my Can Am in the last 15 years or so. It started out as reading full until it got to about 1/2 tank and then the needle would begin moving toward empty, but never going past the 1/2 tank mark on the gauge (that is to say I never let it go past 1/2 before filling it up, and it always took 18-20 gallons). Now it seems the needle doesn't move at all. It's pegged at full.

Is this a faulty ground, or a faulty sending unit? I plan on dropping the tank soon for inspection (and replacing of rubber hoses from tank to hard lines).
Brian, find the sender wire near the trunk. Ground the wire to a body ground with the key on. If the gauge goes to empty, the gauge and harness is good. It should read full with an open circuit or high resistance to ground. Most likely the sender is your problem however, remember that the sender drops to empty with ground so you want to make sure your tank is well grounded.

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