We took a 4.3 inj. Engine installed a small block carb engine, in a 1997 chevy truck. Would like to use the dash. All the lighting works, some gauges work, until you turn the lights on, then everything goes to zero. Weve never got the gas gauge to work, looking for help.

 

OK..these vehicles have some wires that will show negative until you turn a switch on (like the headlight switch) then this wire will turn hot. Several years back I was installing a stereo and the radio would pop a fuse when the lights turned on. I could not figure it out and my mechanic buddy told me about this issue. That was when I found that the ground I was using would be hot when I turned the headlights on. The color of the wire is mostly black with a very small stripe of some other color. (I did not see the colored stripe)

The fuel gauge will operate off of one wire and the body will be the ground(obviously) check the ground wires from front to back and this will most likely be the problem (assuming the instrument cluster has the proper power wires hooked up). Good luck.

Hope it helps.