Surging Tecumseh OHV16

Model number: 13AG675G033 serial:1L096C60045. Engine is Tecumseh OHV16-204216D(H) D.OM. 63265.

Hello again!

This engine has the plastic float bowl assembly. I think they call it a series 7.
I replaced the float bowl assembly 2 years ago. New plug and air filter. It doesn't have the fuel cut-off solenoid on it, but I did install a fuel cut off valve in the fuel line right off the gas tank. I did that on the recommendations of this forum and it has worked well.

At first it started surging right away and seemed to even out after it ran a few minutes. With the blades engaged, it seemed to run better. It sounded better, anyway.
Now, it is continuously surging without any load.

I pulled the line off of the fuel filter and there seemed to be good flow out of it, but hey, what do I know!

Before I pulled the fuel line off the filter I did notice that there were a few air bubbles in the fuel line between the fuel filter and the shut off valve after the mower was shut off. They were not there when I started it. I thought there may be an air leak in the fuel filter or the shut off valve, but would I not have leaking fuel if that was the case?

Oh yeah, fresh gas and correct plug gap and I even ran some seafoam through it.

Where do I start?

 

Take the fuel solenoid out or if it doesn't have one, there will be a drain plug in it's place. Behind that is a spring with a plastic jet on it. Pull that out, and behind that is a tiny o-ring. Most likely this o-ring has swollen nearly shut. Replace the o-ring and clean the jet and your surging problem should be gone.

 

Will do!
Cheese...you the man!
Thanks for the lightning fast reply!
I always appreciate your help and the time you folks put into this place.
Gentlemen and scholars, all!

 

Just a follow up on the surging issue.
Cheese, you were right on the money with the swollen o-ring!
I replaced it and the engine starts easier and the surging is gone. The engine runs great now. If anyone wants to know that part number is 632547. I ordered two and put the other on the end of the emulsion tube (main nozzle). I also replaced the main nozzle spring-part number 632545 and the o-ring around the main jet screw. It is now a fiber washer (part number 27110A).
In the picture the jet o-ring is on the left and the more normal looking o-ring was on the main nozzle.
Now, my question is: was this caused by using gas with ethanol in it, or will the swelling occur using gas without ethanol in it?
Another thing is that it was stored over the past two winters with Stabil in it.
I just wonder if I should plan on doing this every few years.
Thanks again for your time and knowledge.

 

Ethanol does attack rubber, so it could be a factor. The jet is constantly pressing on it too with the spring pressure behind it, so that flattens it out over time. Usually it takes several years to become a problem.

Glad I could help, thanks for the detailed update!