Fuse #13 keeps blowing when key is turned on

need a meter to test ignition system switch--harness--relay -starter

a short in the ign system or ecm will need a meter to test both systems

The other modules on the vehicle have nothing to do with the PCM / ECM fuse blowing . Looking at a electrical distribution diagram to see what all the PCM/ECM fuse power's up an issolate all the thing's one at a time till the fuse doesn't blow any more . Suggest you check out a few video's on youtube on how to find a electrical short . Your best bet mite be to take it to a qualified repair shop that has the knowledge an testing equipment to diagnose this problem . Because it doesn't sound like you know much about it . All the other modules on the vehicle have their own fuse . Something the PCM/ECM power's is causing the fuse to blow . What fuse is blowing ? You don't say ? What code's did you pull an what kind of code reader did you use .
Finding active short
Electric Testing Techniques You Need to Know
ECM Inputs and Outputs Diagnosis

A bad something, yes.
The fuse may be the primary fuse for the key switch. If it is, you would need to disconnect the key switch harness and check for a short to ground on each circuit.

Pull the EFI relay, replace the fuse, and see if it blows when you turn the key on. If it does not turn the key off, reinstall the EFI relay and remove the circuit opening relay/fuel pump relay. Turn the key on. If the fuse blows than we know the problem is One of the O2 sensors, the IAC, the purge solenoid, or the ECM You can unplug the O2 sensors, iac, and purge solenoid. Replace the fuse, turn the key on, and plug them in one at a time until the fuse blows. Replace that component. If the fuse blows with those unplugged than its probaly the wiring and possibly the ECM. let me know what you find and I'll help you more if needed.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

My 92 chevy is still blowing the ecm fuse. I have unplugged the ecm and the fuel pump and it is still doing it. What should I do next

replace ignition switch

if you keep blowing a fuse there's a good chance it's not a faulty part but a short in the main harness most likely under the dash where all the connectors tend to get brittle over time and short out constantly. also check the ecm connection there is a 60 pin type.

1996 GMC 1500 Pickup.
Replaced Coil, Dist cap/Rotor, Ign Mod & pick-up.
All showed to be bad with OHM meter.

20A ECM-B fuse keeps blowing out and I'm afraid to burn these new parts up....

ANY IDEAS OUT THERE???

That fuse provides power for the fuel pump. Either your fuel pump is blowing the fuse or there is a shorted wire.