98 starter clicks, but not turning over.

[crossy]

Alright fellas, when it comes to electrical troubleshooting I know how to use a DVOM, but on late model stuff I really don’t know protocol .
I have a 98 5.7L vortec. I have fuel issues that I WAS troubleshooting, but now it won’t crank. I verified 12.7 Volts at newer battery. The Bendix goes in,’clunk’, but doesn’t turn over. The engine is not seized. The starter gears goes in, but the starter doesn’t TURN OVER. I pulled the starter. hooked 12.5 volts to big terminal and grounded the case. Then I jumped from the big terminal to little terminal, and the starter works fine. I have to assume that there is something that stopped making it’s electrical ‘connection’ in the starting system. I even tried another known good starter. I replaced the starter relay with a new one also. I had it cranking fine, and at one point I did crank it for an extended period, but I THINK it worked again after that time. Is there simply a fuse ,I hope’?? in the system I popped by cranking for too long. I also tried playing with the gear shift lever to no avail. Thanx, Crossy