How I fixed my surging Champion generator

[LittleLebowski]

Problem: Champion 3500 generator (like this one sans electric & remote start) began surging/idling up and down intermittently and consistently during operation after the first twelve hours of operation.

Diagnosis: Main jet/nozzle is too tight/restrictive due to EPA restrictions.

Previous repair attempts: Brand new carburetor, flushing both carburetors, SeaFoam, different types of gasoline with different additives/treatments. Note: Champion power equipment is generally very well known for their superior customer service, but such was not the case for me.

Fix applied: Drill out the main nozzle on the old carburetor using a Dremel tool and first, a .028/#70 bit (this worked fine & I probably could have stopped here), then a .029/#69 drill bit. I used this $4.46 drill bit kit from Amazon.

Results: Perfect operation, no more erratic idle/surging idle. One pull start on months to over one year old 87 octane, Stabil treated ethanol gas. This method worked and I believe that many people whom have given up on their small carbureted engines should try this.

[LittleLebowski]

Bump.

[JohnO]

Nice work! Did you gauge the jet aperture initially? I curious as to how much you opened it.

I have a Honda snow thrower with a hunting carburetor. This past winter it would not run worth a dam. I pulled the carb and ran a wire through the main jet. That got it working but it isn’t perfect. I purchased a new carb and gaskets. Surprisingly inexpensive from a Honda dealer at around $40. I got through the winter without changing the carb and was planning on putting the new carb in when I prep the snow machines this year so it’s fresh. I just may experiment with opening the aperture as I’ll have the original carb to play with.

[LittleLebowski]

Nice work! Did you gauge the jet aperture initially? I curious as to how much you opened it.

I have a Honda snow thrower with a hunting carburetor. This past winter it would not run worth a dam. I pulled the carb and ran a wire through the main jet. That got it working but it isn’t perfect. I purchased a new carb and gaskets. Surprisingly inexpensive from a Honda dealer at around $40. I got through the winter without changing the carb and was planning on putting the new carb in when I prep the snow machines this year so it’s fresh. I just may experiment with opening the aperture as I’ll have the original carb to play with.

Nope, I was working under a time crunch, luckily that worked great.

[RoyGBiv]

Had an early 2000's Kawasaki that benefitted from a slightly bigger main jet and a couple of shims under the carb needles. (4 carbs). Thankfully bigger jets were available to order. Drilling the jets accurately.... 4 jets, all straight, by hand, would be a small miracle for me, YMMV...

That thing was a beast. I don't miss carburetors though. FI FTW.

I had a small (4k) generator surge on me when I got distracted and let the fuel run low. By the time I got to it, it had caused an outlet fire in the wall, inside the house (post hurricane power outage). Just enough to burn some insulation and a burn mark on the wall board, which is how we located the source of the burning smell. We got lucky. Surging generators are BAD.

[LittleLebowski]

Bump.

[LittleLebowski]

Just fixed a friend’s pressure washer that had been dead for a year, using this technique. Works perfectly now.

[camel]

In the past two years I’ve fixed 4or 5 carburetors by drilling them a little larger. I’m ham handed sometimes with little thing like that so I always bought a spare first.