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From: Texas, Republic of Texas/ Founding Member NDCC
Fuse Box
Just purchased a C3 1975. Does anyone know where the Tan wire from my gas sender unit plugs into my fuse box. My gas guage is pegged at 3pm and everything I read stated that this tan wire could be the culprit. The manual I have doesn't have a diagram of the fuse box that states where it should plug in. Any help will be appreciated. I think I knocked it off when I pulled the A/C duct out to replace the brake light switch. Thanks
the gas sender connects to the gauge not the fuse box.
a pegged gauge can be caused by the ground wire at the sender not having a clean connection on the frame.
You can check the sending unit ground connection, under the drivers side rear quarter panel on my '77. Probably the same on your '75. I think it's common for it to get corroded and cause problems. In my experience though, loss of ground causes the gauge to read empty.
From: Texas, Republic of Texas/ Founding Member NDCC
Luckily this car has no corrosion due to the fact it has never seen wet weather I will look for the ground wire in the rear close to the gas tank. I may have to drain and drop the tank as I can find only tail light wires and no Ground coming from the top of the tank to the frame. This happened the last time I went to get gas. Gauge was reading 1/4 tank and I filled it up and when I started the car it pegged to 3pm! I know the ground didn't come loose while I was filling up. I also opened the gas filler cap and took a wood dowel rod and pressed the float all the way down with no change to the gauge reading. Guess I will need to get it up on a lift so I can see better. Thank you all for your comments.
I’m not really sure what the cause of your problem is, but you can probably find the problem at Wilcox’s web site. He has vdeos or instructions on just about any C3 problem. Here’s his fuel page: http://repairs.willcoxcorvette.com/c...el-gauge-info/
I’m sure this will help you find the problem.
Last edited by PeteZO6; Nov 28, 2019 at 08:09 PM.
Reason: Spelling
Basic answer is the tan wire runs with the rear light harness and plugs into a connector at the top of the fuse box. That said, the ground point is normally on the top of the left frame at the rear, shared with the taillight ground. At least on my 69 anyway. I'd follow the information provided for testing.
Fuse Box
I will look for the ground wire in the rear close to the gas tank. I may have to drain and drop the tank as I can find only tail light wires and no Ground coming from the top of the tank to the frame. This happened the last time I went to get gas. Gauge was reading 1/4 tank and I filled it up and when I started the car it pegged to 3pm! I know the ground didn't come loose while I was filling up. I also opened the gas filler cap and took a wood dowel rod and pressed the float all the way down with no change to the gauge reading. Guess I will need to get it up on a lift so I can see better. Thank you all for your comments.
