Suddenly things are going wacky

[Schnauzer]

Regarding my Son's 79 2000 Carb'd. All is fine til yesterday. Suddenly tach and temp guage are going wacky. Temp reads steady at idle then dives to no reading when accellerating. Tach jumps from 0 - 4000 and back. Electric fan suddenly doesn't work. Fuse is fine no wiring changes new thermo switch last year. All of these events started at the same time. Where should I start looking. Also at same time fuse for RR tail lamp blows. Obviously a short there but shouldn't effect guages or fan. I'm stumped.

Please help.

Jim

[Zippy]

I had the exact symptoms you are describing on my 69 coupe in 72. I can't remember what the cause was now but here are a couple of places to start. Two things come to mind from you description. The first thing I would check is the grounding lugs. Not sure where they are on the 79 but on my 78 there is one on each side of the engine bay attached to the fender close to the front of the car. If they are loose they can cause this problem. The other thing I would check is your spark plug and coil wires. Make sure they are all making good contact and are in good condition. Also, make sure they are routed away from your other wiring. Some cables can cause electrical interference.
Good luck.