Im a newbe here with a weird question

[goatman]

Hi everyone im new here and love the forum. I have a 86 Chevy C-20 with a 81 305. My question has to do with the fuel gauge. It drops to empty everytime i turn my headlights on but when i turn them off it registers like it's suppose to. Is it possible that it has a short or could there be something else causing it. My ammeter and water temp gauges aren't working either. I know whats wrong with the water temp gauge but i can't figure out the other two problems. Im not really concerned with the ammeter or water temp gauge problems cause im planning to install a seperate voltmeter and a mechanical water temp gauge. I still would like to fix the fuel gauge problem so any help would be appreciated. Thanks in advance

goatman john

[mudseeker]

sounds like you need to break out the multi-meter, no easy way around it.

[junior3382]

yeah, I agree with mud, you have two wires touching someone and there is an uneccesary power drain somewhere and you will need to identify where it is. Multi meter is the best route to go.

[gmctrucks]

I third it. My 57 Ford had the fuse box on the ignition swicth well one night my brother that had it before me noticed that smoke was coming from under the dash so what he did is just wrap the wires together in the middle of the night well he never got around to fixing it so then I got the truck I was on my way the work and it just shut down I was so mad that I honked the horn and it started right up it was funny well I waited for the weekend and rewired it correct I will never forget that it was in 1980.

[goatman]

I kinda figured that was going to be the answer but one can always hope. I thought maybe someone on here might of had a similar problem and could tell me where a good starting point would be. Anyway, thanks to all for the help

goatman john

[crabtruck]

Welcome to the forum John.
Normally I would think you are grounding out the sender wire when the gauge goes to zero like that,
but since you are adding power to more wires when you turn on lights,
and you don't have blown fuses or other problems, I think not.

I would recommend a good visual inspection of wires under dash while operating the switch.
Look for movement, you may have wore through the wire causing it to ground out or loosened a connection.
Then try to cause the problem with lights off by moving the wires around by hand.
This may be faster than a meter check and won't require identifying the wires first.
Good luck.