Onan generator problems

I have a 2001 Onan 17KW MDKAD generator. It has 3800 hours. At some point someone cut the engine overheat sensor and the exhaust overheat censor. The generator overheated. I had the gaskets in the fuel injection pump replaced and the generator reserviced with coolant. I also had the engine overheat sensor and the engine exhaust overheat sensor replaced and reconnected. The generator ran normally for about 15 minutes. Then it automatically shut down and was dead as a door nail. We had technicians trace the problem to CB2 which they replaced. The engine once again started and ran for about 15 minutes. CB 2 popped and instead of disconnecting power to the start solenoid it cut off power to the fuel pump and the engine ran out of fuel. We called technicians from Shearwater in Stuart. They replaced the fuel pump with no difference. They devised a work around. I run a pigtail from the start solenoid directly to the fuel pump. CB2 still pops out after about 30 seconds but the generator continues to run.

At my electrical panel the light in the start switch remains on. Not sure if that's normal. The voltage indicates low, roughly 8 volts, even though the voltage at the start solenoid is 14.3. So I'm losing voltage somewhere.

Any ideas would be appreciated!

The 8 volts is the reading on the gauge on the electrical panel next to the other two gauges, oil pressure and temperature. Those two readings are normal.

Is it normal for cb2 to shut down the engine by cutting off the fuel? I thought it would cut power to the starter solenoid.