Rough running Generac

[MajorCavalry]

My brand new Generac 20K Guardian has been exhibiting some rough running during its weekly exercise. It is running on CNG. Proper pressure is verified. It is running in quiet mode, 2400 rpm. I can smell unburnt CNG from 20 feet away.

The installer returned and ran it in normal power mode, 3600 rpm and it seemed much smoother. Seems like the automatic choke is the problem. A factory tech is scheduled to eval and repair/adjust. Any ideas?

 

[RiceCake]

Whats the point of a choke system when its running on CNG -?

Least you got a tech coming.

 

[lockguy]

Originally Posted By: RiceCake
Whats the point of a choke system when its running on CNG -?

Least you got a tech coming.


why would you not need choke whether running on cng or anything else? choke is to help get the motor started and warmed up regardless the type of fuel. the fuel/air mix has to be right for the engine to run correctly.

 

[Donald]

Originally Posted By: lockguy
Originally Posted By: RiceCake
Whats the point of a choke system when its running on CNG -?

Least you got a tech coming.


why would you not need choke whether running on cng or anything else? choke is to help get the motor started and warmed up regardless the type of fuel. the fuel/air mix has to be right for the engine to run correctly.



I have a Winco LP gas generator and I am pretty sure there is no choke.

Why a choke is needed from Wikipedia:

Choke valves are important for naturally aspirated gasoline engines because small droplets of gasoline do not evaporate well within a cold engine.

 

[Donald]

What is "quiet mode" at 2400 RPM? If its a 3600 RPM engine then it cannot produce proper 60 cycle electricity at 2400 RPM.

Does the weekly exercise just start the engine but not load it at all? Or maybe it loads it with an internal load that is a heater coil (or similar) that will not care if its 60 cycle or not?

I am surprised a 20 KW generator is not 1800 RPM. Thats is what you really want to not burn through a lot of gas.

 

[MajorCavalry]

Originally Posted By: Donald
What is "quiet mode" at 2400 RPM? If its a 3600 RPM engine then it cannot produce proper 60 cycle electricity at 2400 RPM.

Does the weekly exercise just start the engine but not load it at all? Or maybe it loads it with an internal load that is a heater coil (or similar) that will not care if its 60 cycle or not?

I am surprised a 20 KW generator is not 1800 RPM. Thats is what you really want to not burn through a lot of gas.


The weekly exercise period is a 12 minute running of the engine with an internal fault check. The generator is not loaded to simulate generator function. It runs at 2400 rpm to be more quiet and use less gas. Being an air cooled generator, it runs at 3600 rpm under operating conditions. This is consistent with 20K Kohler and Cummins generators. Water cooled versions run at 1800 rpm.

Confirmed with the owners manual that it does indeed have an electrically operated choke controlled by the electronic control panel.

 

[lockguy]

Originally Posted By: Donald
Originally Posted By: lockguy
Originally Posted By: RiceCake
Whats the point of a choke system when its running on CNG -?

Least you got a tech coming.


why would you not need choke whether running on cng or anything else? choke is to help get the motor started and warmed up regardless the type of fuel. the fuel/air mix has to be right for the engine to run correctly.



I have a Winco LP gas generator and I am pretty sure there is no choke.

Why a choke is needed from Wikipedia:

Choke valves are important for naturally aspirated gasoline engines because small droplets of gasoline do not evaporate well within a cold engine.


point taken. There would still need to be some kind of adjustment though right? If its running at a lower rpm, then the fuel/air mix would be certainly scaled down, but maybe not the same ratio? depending on load, rpm and whatever else, there may be some kind of variation that would require a choke of sorts. just random thoughts....