Generator Surging

[jking]

I have a Kohler 7kw propane powered generator in my '84 310 and when we run it, it won't hold a steady rpm. Even under load, it speeds up and then slows down and then speeds up and then slows down and ... Does anybody have an idea (a) what causes this, and (b) how to cure it? I don;t think there is any serious problem, as the output current is pretty steady or at least seems so, but it is annoying at best and possibly harmful.
Thanks for your expertise. Jamie

[Keyair]

I don't know, but mine did that when the oil was low....

[John H.]

check the fuel pressure

[DaveFL]

If the gas line was sucking air it would surge. Find the manual it should say what gas pressure is required. Kinked lines could cause. Surging on a gasoline generator happens when the carb needs cleaning of old gas residue, with propane it might be the flow setting. Reduce the load and let it warmup longer, after spraying carb cleaner in the air filter has been my easy fix. Did you check the air filter and it's summer winter position for air intake.

[r carl]

Some water in the carburetor will cause that. Does the float bowl have a drain plug?

[AirRowan]

I had a bad spring on the govener arm. It was hunting (surging) badly voltage would go from 80v to 150v 40Hz 80Hz. If yours is surging do not run any compresors (AC, Ice maker, blender etc.) your charger should keep up with it.

[Gypsy Jo]

no expert but I was having surge problems with my gas onan. It was the choke.
Jo

[TXiceman]

When was the last time the generator had a tune up, new spark plug, fuel filter, etc.?

Ken

[Keyair]

He said it is Propane powered....

[thecatsandi]

Since it is propane. I would go with the generator governor and then the pressure.

[vswingfield]

Originally Posted by r carl

Some water in the carburetor will cause that. Does the float bowl have a drain plug?

Propane carburetors don't have floats or float bowls. The propane carbs are very simple and reliable. My experience has been that the regulator can cause problems like this.

I worked on large stationary engines and saw this occasionally, though rarely. The fuel gas (propane converted to a gaseous state) pressure needs to be held constant, for the carb to work properly. It is possible that the diaphragm in the carb is sticking or has developed a pinhole(s), but I would check the pressure first. If there is a problem, replacing the regulator is a simple fix.

As mentioned earlier, checking the governor linkage and spring are worthwhile.

[jking]

Thanks to everyone who responded. The propane pressure is steady and within tolerances, suggesting the regulator is OK, so I checked out the other ideas and found the spring that holds the governor arm back was perished. A simple replacement fixed the problem. This forum is truly amazing!
Thanks again,
Jamie

[Keyair]

Awesome news!
Good detective work on your part!

[AirRowan]

What kind of propane set up factory or something after market? Hi or low pres? Do you have a vacume shut off and how much propane do you burn an hr 1# or more? I need to switch my system over and I do not know what one to go with.... I am changing my fuel so I no longer will carry gas and do not feel like dropping 10k on a diesel! Here are some of the propane webpages