Tach bounce problem

Hello everyone,

Recently the tach on my '73 911T has been bouncing all over the place.

This happened last year and I fixed the problem by cleaning the contact between the tach wire and the distributor.

This week-end I tried the same trick - removed the wire and cleaned up the contacts as best I could with a wire brush and emory paper.

But - no dice, in fact, the problem seems even worse! The tach is mostly dead, occasionaly swing into life to give an approximate reading, the bounces down to dead again.

Two facts may (or may not!) be related to this problem - my oil level guage seems to be reading high (regardless of the oil quantity in the tank) and the low fuel warning light comes on even when the tank is full...

I'm wondering if the problem is actually a bad earth somewhere near the instruments themselves? Perhaps one of you knows if these instruments have a common earth?

Two other facts - the temprature and pressure guage seems to be absolutely fine, and the engine itself is running well, so I don't think the tach problem is related to the CDS box.

Thanks,

- roGER

Roger,

Check all your ground straps. I had a similar problem last summer and the ground strap from the battery had eroded just enough to cause similar electrical problems!

Huey581
86' 911 Cab

IN additon to ground straps.
Double-check your point gap. Also check your rotor for wear (side to side movement).

Good luck.


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Nick Hromyak
'85 Carrera

Roger,
I had the same symptoms on another car (MG) and it was loose/disintegrating fittings for the wires at the starter. Just another place to check..
Good luck.
Craig