I'd check the fuse's or circuit breakers. Then I'd look for a bad connection in the idle circuit. Did a google search "Pow'r Guard R45 4500/4000 Generator" and found this.
http://www.baldor.com/Shared/manuals/g00269-303.pdf
If you can't fix the problem I'd look for a way to simply bypass to idle solenoid. Just make sure that the governor can still control the engine speed.