GT275 Engine Surging

[snpower]

I have my father's GT275 in my possession; It has been at my mother's property and would not turn over or start. I replaced the fusable link, and the seat switch to resolve that. It starts normally, but the engine surges. The RPM's drop somewhat about 3 - 5 seconds. It is worse with WOT and when you press on the hydrostatic pedals. I filled the tank with fresh non ethanol gas, poured in some seafoam, and let the engine run for probably 75 minutes and also mowed my yard with it. It seems fine save for the surging which is again, worse at WOT and when accelerating.

I do know that the machine was serviced by John Deere 1.5 years ago. The fuel tank and system were drained/cleaned and I believe the carb was cleaned but I am not 100% on that.

Thoughts on what I should check?

 

[5030]

Carb is gunked up. Time to take it off, take it apart and give it a good soak in something like Berryman's Chem Tool and put it back together. You have a partially plugged main jet / emulsion tube.

 

[Carl_NH]

As 5030 says likely carb - you can clean bowl and jets, but I had cleaned/fixed the Kohler Magnum carb on my 35 YO Cub cadet several times, so decided to try an inexpensive replacement carb for $30 - after replacing it starts much easier (fires off in seconds vs cranking for 15 seconds) and runs better.

 

[snpower]

5030 was correct! I thought that might be the direction to go but was glad to have confirmation. So, thank you both for replying.