Thread: temp gauge acting strange

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I am finally ready to fire the truck up after the rebuild. When the starter is cranking the temp gauge peaks to high until I let off the key. The wires are on opposite sides of the motor and dont really come into contact in the loom.
any ideas?
1989 GMC K2500
TBI

Check the ground to the body. Bad grounds can do all sorts of wierd things to gauges.

I agree with R Pope. If your battery is grounded to the body or the frame, make sure you have a ground strap (cable) from the engine to the body or frame or, better yet, run your ground from the battery direct to the engine block if possible. It sounds like your starter is seeking a ground through whatever route it can find; it will eventually start melting wires...

You can test this theory by hooking an ordinary jumper cable from the ground post on the battery to somewhere on the engine. Make sure you have a good connection; then crank it and see if the gauge still does that. Let us know what you find out.

everything that sits on rubber mounts needs a jumper ground to cross the rubber .. sometimes people dont hook little ground straps back up and wonder why their shift cable melts stuck..

And todays throttle cables as well

I was recently at a shop where they were going to start a supercharger 427 Ford in a high dollar Eleanor car--they had moved the battery to the rear of the car, braided fuel lines to the tank to the carb

while cranking the fuel line was smoking where it touched the valve cover---
I left the building----

Off this subject, but , if you have braided AN brake lines and have any welding done on your vehicle, check out the brake lines before you do that burnout in the parking lot

Jerry

there are 3 grounds from engine to frame and 2 from frame to body 1 each from battery.