Fuel gauge erratic
Thread Starter
6th Gear
Joined: Apr 2020
Posts: 6
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From: New Zealand
Fuel gauge erratic
Hi. I have a problem with my 69 C3 fuel gage reading inaccurately and occasionally the needle going hard over past the full mark. Is it likely to be the sender unit in the tank?
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
Possibly... But it is more likely to be a bad connection on the ground wire for the sending unit due to corrosion or a broken wire inside the insulation. Vibration of driving causes wire to flex and gauge to be erratic.
Is my vette stock?? HAHA
Joined: Oct 2015
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
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go to willcox's trouble shooting page. It shows the dial indications and there cause, but I agree with 7T1vette on the ground possibly going bad
Instructor
Joined: Jul 2012
Posts: 171
Likes: 22
From: Kentucky
I Have similar issue with my 80 gauge seems to work shows full to empty but has a bounce to it when I drive. Not all the way from full to empty but slight movement. I suspect sending unit. Has gotten some better after I added techron Hopefully will improve as I drive more. Car had set for a while with only a little gas in the tank.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
Yep. If the car sits for an extended period with low fuel in the tank, the resistance portion of the sender and its mating wiper contact can corrode and leave a dead-spot on that slider wire. The gauge will read properly at other points, but when the tank is at that same level it will 'hunt' for the right resistance value to send to the gauge. At least your gauge is still reading accurately most of the time.
If you gauge does that at various tank levels, you are more likely to have a ground signal problem.
If you gauge does that at various tank levels, you are more likely to have a ground signal problem.
