Onan generator developing slight surge

[DAS26miles]

My 3 year old Onan 4K has 150 hours on it and I have properly exercised it every month when not in use. Last week, I noticed a slight surging under load and with out. My Killawatt showed a drop of .2volts. I have half a tank of full in the 55 gallon tank of the Class C. Will adding Seafoam clear it up or perhaps draining the bowl and shooting carb cleaner inside and letting it sit work to solve it? I hate to take it in for service if I can clear it up by DYI.

[DAS26miles]

Yeap, Seafoam worked, no more surging! I don't know how many times I've walked thru campgrounds hearing surging generators. They need to do this clean-out for $18 with gas.

[DAS26miles]

Currently doing the clean with Seafoam. Got a can of Seafoam and 2' of 1/4" fuel hose and clamps. Followed Seafoam's Official Youtube video instructions but used 16 ounces in 1 gallon of gas instead of 1 pint of gas. So it's not as strong as that in the video. At last phase now running after HOT clean-out. I don't hear the rhythmic noise I heard before, so perhaps it's cleaned out what ever was causing it. Still have 1/2 gallon or more of gas. Guess I can just put it in the RV fuel tank.

[theoldwizard1]

Surge is almost ALWAYS caused by a blockage in the carburetor primary/idle circuit. Seafoam is good. Anything with polyetheramine (PEA), aka Techron, is also good.

No guarantees ! Use up the fuel that you have a replace it with fresh. Gasoline does not like to "sit around" for more than 4-6 months.

[ScottG]

Use some of the SF to spray clean the gov. spring and related parts.

[marcsbigfoot20b]

Try sea foam first and run it for a while. If it still does it, there may be a worn governor spring or adjustment needed. Just made an adjustment today on my 2500LP for surging.

[azrving]

I would absolutely try sea foam.For the price it's well worth trying before ending up smelling like gasoline.

There is no guarantee that it will fix your problem but if it does than you would pretty much assume that it was a blockage which caused a slight lean condition.

Gasoline doesn't sit around well in small engines. 2 strokes seem to do better than 4 strokes since they usually have diaphragm carbs which aren't open to atmosphere. Four strokes carb bowl is vented to atmosphere.

If it fixes it you might then run seafoam on some schedule. I don't believe in piston ring replacer in a can but I have seen seafoam work many times.

[gbopp]

I wouldn't worry about a drop of .2 volts.

The Onan 5000 in our 96 Southwind was slightly surging. I got a can of spray Seafoam, removed the air filter and sprayed into the intake while the generator was running.
I stopped the generator and left it sit a couple hours, then repeated.
It took care of the surge.

When was your generator fuel filter changed?