Hello, I have a Dyna Generator with a B&S Vanguard 15HP Motor. The motor starts easily either manually or by using the electric start. The problem is that when the choke is opened the engine just surges like it's hunting for the correct RPM. If I pull the choke out again, it smooths right out and purrs like a kitten. I'm pretty sure the problem is in the carb but I was wondering if there are any chemical additives I could use to try to clean it out so it runs smoothly without the choke. I've thought maybe SeaFoam, but I'm not sure if that will be enough to clean it out. Looking at the carb, it looks almost like new but to remove it looks like it could get complicated because the mouting bolts seem to come from the bottom, so that would involve removing the intake manifold to get to them. I really don't want to invest in a full set of gaskets for the manifold and the carb if this could be simply remedied by adding a cleaner to the fuel. Any suggestions or thoughts on the pros and cons of a cleaner additive would be appreciated.

Hi,
The one I see recommended by others is Seafoam, which comes in several varieties and is well known amongst outboard engine mechanics.
Peace,
Clarke