[jclark003]

It sure sounds like a control issue but if you verified all the sensors (high engine temp, low coolant level,etc) and replaced control board and fuel pump it sounds like you have covered the usual suspects. This is gas powered correct? If so possible engine ignition issue or connector issue in the engine harness. May be worth it to check/clean all the connectors (following usual safety procedures).

Otherwise try reaching out to flightsystems Inc ( [Only registered and activated users can see links Click here to register] ). They provide/manufacture a lot of replacement parts for generators (electrical and control side) and are super helpful in troubleshooting. They have a lot of experience and may be able to give you some answers.

Sorry hope you get it worked out.