I have a somewhat older Briggs 9hp vanguard engine on a BCS tiller. It was something my neighbor picked up and doesn't know much about it. When he got it, it would run a little bit then die out shortly after starting. I drained and flushed the fuel tank, lines, and filter. I also cleaned the carburetor, and let it soak for a couple hours. It wasn't very dirty, just some sediment at the bottom of the float bowl but I took all the jets out and cleaned them as well. I can now get it to start up easy and run nice until I bring the throttle up about 1/4 of the way, then it will start to surge a little every few seconds. I tried adjusting the mixture screw on the side of the carb but it makes little to no difference. I have taken this carb apart and cleaned it several times now but nothing changes how it runs. If I put the choke on just a small amount it will run better at the higher speeds. I was thinking about maybe enlarging the main get just a tiny amount to see if that fixes it, as ive had luck in the past doing that but that was on my own stuff.
Does anyone have another other suggestions before looking into a new carb or messing with the jet size? I have put a new plug, fuel filter and air filter on this engine too.
Model number: 185432-0538-A1
Serial Number: 96031449
