Small Engine Troubleshooting Problems? Ask a Mechanic Now.
What is the serial number of the genset?
It is odd that no warning lights are coming on, but it is possible that a light is burned out.
The first thing you need to do is to bypass either the LOPS (low oil pressure switch), or the HTS (high temperature switch). See if the genset will run for more than the 20 seconds.
If so, that system is at fault.
If it still shuts down, reconnect that circuit, and bypass the other one and test run again.
If neither of those determine the problem, we will have to dig deeper.
The next thing is to get voltage and frequency readings from the unit while it is running for those 20 seconds.
How much voltage is being produced, and at what frequency?
I am a certified Generac technician, and have been for 15 years.
You stated in your last reply, and I quote, "Bypassed both lops & hts still same resaults will start run 20 secs shut down and repeat "
Now you say it wouldn't start, and wouldn't even crank. Which is it?
How did you bypass the switches?
That is not how to bypass the LOPS and HTS. To bypass them, you disconnect the wires and tape them off so they can't touch anything. These are both NO switches.
Ok, get the voltage and frequency readings. Lets make sure the power is not the problem.
The best place to get the readings is directly at the circuit breaker on the genset, with the breaker turned off to eliminate any outside interference.
OK, if you have no power coming from the genset, you need to do a test called the Fixed excitation/Rotor amp draw test.
Click here to download the procedure.
Let me know the results.