Did you check the isolator block it could have a crack? Did you get the carb cleaned out like in the video, this guy used 10% Purple Power and 90% water in a heated ultrasonic cleaner to get the tiny airways cleaned out. Then he blew through everything with an air compressor. The motor he worked on surged just like how you described. When he was done it ran strong and steady.
Yup, replaced it as it did indeed have a crack. I did that at the same time I first cleaned the carb.
I did clean it after I had first installed it because it still didn't run right. I found sand in the jet when I took it apart. At that time I cleaned out the tank and replaced all lines and filters. It ran ok after that but still not perfect. I am going to pull the carb again this weekend and see if there is more chit in it.
Well, I didn't pull the carb yet. Instead I replaced the engine . A member here at FHC hooked me up with a replacement engine from his fil's pressure washer. I bought the engine as well as a new hose and wand for my pressure washer that was leaking all for 50.00. The engine fit perfect and ran awesome ! Anyway, I'm back in action and will take the carb apart on the old engine when I get a chance, so I have back up for the splitter or power washer. Special thanks to cnice_37 for hooking a brother up. You da man
You forgot the Budweiser... they helped ease the tension watching that divisional game! Glad it worked out.