63 fuel gauge not working
Fuel gauge checked and determined faulty. Checked new gauge and works fine out of dash. Using battery and grounding and puting power to it. Installed the new gauge and it sits at half tank and will not move while raising and lowering the float. Put trouble test light at the gauge end and raise and lower float light goes bright and dim as you move the float. That shows wiring good and sending unit is working. Could there still be a problen there. Any ideas on why this gauge would not be working. Has anyone ever had a grounding problem with the fuel gauge. It only grounds at the bottom stud to the cluster. Wiring harness is new. Cluster has been out twice I don't want to pull again if possible.
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Re: 63 fuel gauge not working
Mike -
Try this - may be helpful.
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Re: 63 fuel gauge not working
John, I got that from you when I was working on my car. It's great for trouble shooting. Cars is at a friends and he didn't have a multi-meter. I'll go back over tomorrow with mine and check the tank sending unit. It appears to work but not sure if its putting out the corrrect ohms.Comment
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Re: 63 fuel gauge not working
Mike, there's also a trouble shooting by symptom section in the 1963 Corvette shop manual. One of the common fault symptoms deals with the gauge not reading either below or above 1/2-full...Comment
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Re: 63 fuel gauge not working
Mike,
also, make sure to check all the spad connections at the gauge as one of them could have worked looseRick Aleshire
2016 Ebony C7R Z06 "ROSA"Comment
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Re: 63 fuel gauge not working
Didn't look in the troubles and rememdies.
Thanks Jack for that.Comment
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Got it working
Cluster had to pulled again. Found paint on the surface that the gauge mounts to. Took steel wool and removed paint . Gauge works now. It must have not been getting a ground through the painted surface. What I can't figure out is why the amp gauge still worked, same surface.Comment
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Re: Got it working
Difference lies in the unique circuit topology of the Whetstone bridge design of the '63-67 fuel reporting system. It requires TWO mutual ground points (dash and tank) to make the divider bridge work properly.
The reason for the Whetstone bridge circuit was to make the fuel gauge pointer needle position TOTALLY INDEPENDENT of specific B+ voltage (Is the battery low on charge?...Is the alternator running at max charging current?).
Cars before this era simply let the gas gauge pointer fluxuate in lock-step to specific battery level. Cars after this era had MUCH improved on-board voltage regulation. Neither used the added sophistication of constructing the variable resistance of the gas tank sender into a voltage divider bridge that rendered the gauge completely independent of specific battery voltage.
The design was SO unique that shop/service manuals from that era devoted a special section explaining to mechanics how to understand and troubleshoot the gas guage system...Comment
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Re: Got it working
True, except that the service manual diagnostic procedure assumes you have access to a "known good" new sending unit and gauge to use as test devices; not too helpful for the home mechanic. That's why I wrote the article so all you need is a multimeter.
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