Any Luck with this?
I have been having exactly the same problem with my '95 Prostar with the LT-1.
At EXACTLY 2100 RPMs, bogs down, back off, right back up to 2100 RPMs, but bogs down again. Seems pretty clear that something is causing it to go into 'Safe Mode'. It was running a little hot, so I thought maybe that was it.
After lots of research, I:
- replaced the impeller and made sure closed cooling system is running clear
- drained and cleaned the tank
- checked the pickup screen
- changed the fuel filter
I ran it for a while on the trailer and the temp was stable at 180. I know that running it on the trailer or in neutral isn't a substitute for a real water test, but the lakes are so high here in NJ that they are no-wake lakes, so I can't really test it until later in the week when the water goes down...
Next steps are to:
- change the thermostats if it runs hot again
- pull the Fuel pump to check the screens
- check the fuel pressure
Let me know if you had any luck on your problem. That shutdown at exactly 2100 RPMs makes it seem like an electronically controlled situation more than a mechanical, but I guess it could be electronically controlled based on a mechanical problem...