Hi, I'm new to this forum. I just bought a 1996 Suburban with 226,000 miles on it. It has the 5.7 vortec gas engine in it. I have owned other Chevy full size stuff in the past, but this is the latest model I've owned. It runs well, but the tachometer jumps all over, especially when accelerating. Yesterday after driving it about 40 miles, the tach stopped completely. There are no other symptoms, it idles smooth and has great acceleration. No ignition misses or codes. I did install a beefy ground wire to the engine, but that did not help with the tach problem. Where is the tach lead on these? Does it plug into the distributer like the old HEI ones? What color wire? Also, how many miles are people getting out of these Vortec engines when maintained?

 

Probably need to replace the tach stepper motor inside the cluster.

Most people are getting 226,000 miles out of the 96 Vortec 350 mills before they require an overhaul.

 

If it is not a loose wire, I have read that it could be caused by a short or open ignition circuit such as a loose or defective plug wire, bad distributer cap, carbon tracking in a cap, or a bad tach. Can just the tach be relaced? SOme people have told me the tach problem on my Suburban is very common on GM trucks of that vintage.