hitchell

66 big block with transistor ignition. Compression good, timing correct, getting gas and spark. Will crank and run very lousy with skipping and backfiring for a few revs then quit. Almost acts like a bad vacuum leak but is not. No cracks or carbon tracks in distributor cap. When cranking over, timing light shows consistent spark. Spark is evident when plug is removed and grounded to engine. Could this be a problem with the pulse amplifier or are they either good or bad?

JohnZ

I'm not a T.I. guy, but the two most frequent failure modes are a bad ground at the amplifier, and moisture inside the amplifier case. Is it an original amplifier? That's 40-year-old germanium transistor technology, and the current replacement guts are a huge improvement according to the guys that have them.

Corbrastang

Check out long island-they have the new circuit boards and the new Ti pick up coils. Its a lot cheaper just to replace those two units than to send it off to one of the few rebuilders. I'd start with the amp circuit board as John Z suggested. It is very simple to replace.

67L36Driver

The above and; twist, push and pull on the coil while it's running. You may have one that's gone bad. I chased a 'lean cruise miss' for over a year because of a sneaky coil.

Carefull of the high voltage lead, you can get bit.