i have a 1991 z28. the starter stays engaged when the engine is started. i have replaced the complete starter and starter relay, but the starter continue to engage when the engine is running? has any one had this type of problem?

 

Sounds like either the solenoid is still getting power from the relay after the key is let go,or the starter isn't shimmed just right and the pinion gear and flexplate are too tight when the starter engages, and therefore the starter can't release itself from the flexplate.It may be just right for it to engage into the flexplate teeth,but just tight enough to keep it in there.

 

I was going to say that your solenoid contacts are likely welding, but the new starter should have taken care of that. Saving that, there is about a 95% chance that the starter solenoid/pinion shaft is mechanically binding, and a 5% chance that the ignition switch is hanging up. When it hangs, watch the temperature gauge to see if it stays "pegged", as when you are cranking. If it does, the switch is suspect.

 

I had the exact same problem with mine. It was shimed too tight. Try adding another small shim and make sure you flush the starter to the block before you tighten the bolts.