I'd start with removing the remote start unit. Now, that probably won't fix it, but it worked before the r/s unit was installed, so at least with the r/s removed you can see if that somehow causes the problem.
If that doesn't stop the breaker pop I'd still leave the r/s off until the unit is working again.
It would be important to know exactly when the breaker pops. There are a couple of timing actions here, mostly around the fuel solenoid and the starter disconnect switch.
Fuel solenoid engages from the starter solenoid (PULL) , but is held (HOLD) on by a relay once the starter disconnects.
The starter disconnect switch disconnects the starter and moves some 24 vdc around once the engine reaches a certain RPM.
Depending on exactly when the breaker pops the problem could be traced to other circuitry based on what those two things are doing at the time.
NOte that the starter disconnect switch looks like just anther relay in the control box, but upon inspection it is not a relay, but a logic circuit board inside a relay housing. It's on the far left of the relay banks. It is possible to install that switch 180 degrees out which will cause an OIL PRESSURE fault when trying to start. It is also possible to install that switch so that not all contacts connect in the socket. If you haven't fooled with that switch then it should be OK -- I'm just passing that info on in case you need to get into the circuitry that involves that switch.
I have had that circuit breaker pop when there was a problem with the fuel solenoid wiring. I don't think that the generator "likes" to have the PULL and HOLD circuits on at the same time. If, somehow the PULL remains on when the HOLD is energized the the unit would do exactly what you describe - shut down after it just started to make some AC 'cause the two coils of that solenoid draw in excess of 7.5 amps.
good luck - shorts are easy to find when there is smoke and burning, but when it is intermittant it gets more difficult.
z
