Odd Electrical Issue
10-17-2017, 07:28 PM
#1
Instructor
Thread Starter
Odd Electrical Issue
I hadn't driven my bone stock 72 for about a month. Gas tank is about 3/4 full but when I started the car, the gauge showed less than 1/4. So I checked with a flashlight and tank looked about 3/4 full as I left it. When I put on the headlights, the fuel gauge moved to way past the full mark. Lights off and it goes back to <1/4. I tried it with just the instrument panel lights on and the gauge didn't move. Any thoughts??? Thanks
10-17-2017, 08:23 PM
#3
Instructor
Thread Starter
10-18-2017, 07:56 AM
#5
Team Owner
There is a Black? wire going from the tail lights to the chassis frame, in there is spliced a pigtail that comes from the fuel tank, that wire corrodes a bit at the chassis....pull it and clean off the steel/connector loop to shiny clean metal....then snug it down solid, check that it all works, then cover the bolt/loop/chassis area with black automotive RTV to make it water tight forever.... AS I RECALL the right lights and the tank are grounded together, and the left lights have their own ground...so may as well to them too....while you at it, the battery does the same trick off the negative terminal....may as well do it too.....
10-18-2017, 02:05 PM
#6
Instructor
Thread Starter
There is a Black? wire going from the tail lights to the chassis frame, in there is spliced a pigtail that comes from the fuel tank, that wire corrodes a bit at the chassis....pull it and clean off the steel/connector loop to shiny clean metal....then snug it down solid, check that it all works, then cover the bolt/loop/chassis area with black automotive RTV to make it water tight forever.... AS I RECALL the right lights and the tank are grounded together, and the left lights have their own ground...so may as well to them too....while you at it, the battery does the same trick off the negative terminal....may as well do it too.....
10-18-2017, 05:13 PM
#7
Melting Slicks
Member Since: May 2015
Location: Cape Girardeau Missouri
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Lark327
I suggest you check the AIM (assembly manual) for your chassis grounding points and clean them ALL.
The fuel gauge in my '79 had a similar bizarre problem after I did some electrical upgrades that involved removing the front lamp harness during which I nicely cleaning the grounding points. Goofy electrical problems ensued until I cleaned ALL of the chassis grounds AND all of the electrical connectors outside the cabin! As a result of this lamps burn brighter, the HVAC fan blows far better, wipers move faster, etc.
I suggest you check the AIM (assembly manual) for your chassis grounding points and clean them ALL.
The fuel gauge in my '79 had a similar bizarre problem after I did some electrical upgrades that involved removing the front lamp harness during which I nicely cleaning the grounding points. Goofy electrical problems ensued until I cleaned ALL of the chassis grounds AND all of the electrical connectors outside the cabin! As a result of this lamps burn brighter, the HVAC fan blows far better, wipers move faster, etc.