Strange Generator Issue

[_Me2_]

My trailer has an Onan Microquiet 4000 that has started having an intermittent problem, although it is becoming the rule more than the exception now.

When I try to start it, it will crank for maybe 1/2 a second or so and then stop. It will keep doing that if I hold the button down. Sometimes it will fire up and run perfectly, but that is becoming few and far between. I am not getting any errors lights.

The batteries are strong and I have checked and cleaned the connections. I took off the start relay and it tests out fine, with 4 ohms across the coil and there is continuity across the terminals when the coil is energized. My next thought is starter or control assembly, neither of which am I looking forward to working on. I am leaning toward the control assembly since it's not giving me any error lights. Any ideas?

[_Me2_]

I jumped the start relay and ground directly to the battery to eliminate any connection and ground issues, and it does the same thing. I also jumped my truck to the trailer batteries (couldn't get close enough to jump the generator directly) and no change. I tested the voltage and it jumps up to almost 12 and then drops to zero each cycle (as though something is shutting off the coil). I even connected a jump box directly to the generator side of the start relay while also using the start button, and it does spin a bit longer than usual, but it still doesn't start.

[_Me2_]

Thanks for the ideas. I will make sure the grounds are good. I'm not sure that I can check the voltage accurately because it will cycle trying to start every second or so, but I will try. It does exactly the same thing from the indoor switch and the switch on the generator.

[Chris_Bryant]

Is it the same from the remote as the genset switch?

[eHoefler]

Check the voltage while cranking, if it drops below 10 volts, you have a power to the generator problem.

[ksg5000]

Try checking/cleaning the chassis ground wires - both the generator and battery.

[Chopperbob]

It needs power to run. Mine did That. It was a
Regulater, stator, and field. Could be something
Simple but We Had To Take ours to a cummins
dealer.
Bob