Saw in the FAQ that a dead tach can indicate a problem with the Hall Effect Sensor. The tach wasn't moving when it wouldn't start, so I pulled the wire and saw that the wire, which is old, had "cracked" in a few places.

I figured the HE wire might have been grounding out on the manifold. I don't know if that was the problem or not, but I cleaned it up, patched any visible cracks outside the sheathing (under the manifold) with electrical tape, reconnected and it started up. However, it then stalled out about 30 seconds later, restarted and then ran strong for the most part.

I've since gotten it to run fairly regular at this point (will hold idle), but just a moment ago when I went for a test drive I again got the jumping tach, with the tach going down to zero and up to 3000 in just a few seconds. Drove it without a problem (stopped, revved, drove, etc.), but the recurrence of at least one symptom convinces me that I still have some kind of issue.

So, what else could cause these kinds of crazy tach fluctiations, stalling (drops out of idle), refusal to start when cold, etc. I should also mention that the car is hot now (operating temperature), and when I had all the problems it was cold, so... could the problems still be there but just masked because the car has warmed up?

If anyone has any thoughts I'd love to hear them.

Thanks,
rt