Need engine help

[cyaw126]

Have a Briggs 219907-0131E1-050823ZA that is having high speed issue. Just got this and trying to get it cleaned up to resell. Starts fine and will idle at low to medium speed but if you adjust it to high speed it will start sputtering and blowing black smoke like its getting to much gas and just fall on its face and barely run. I took carb apart and blew carb cleaner through all passages and still doing the same. This is a Nikki carb, I have had these carbs have problems on the idle circuit but never on high speed circuit like this. Any suggestions would be greatly appreciated. Thanks

 

[ILENGINE]

Did somebody take the carb apart and loose the jet that sits in the bottom of the plastic piece.

 

[cyaw126]

Did somebody take the carb apart and loose the jet that sits in the bottom of the plastic piece.

I did take the carb apart but made sure the jet was in the tube when putting back together. Could a spark plug that breaks down under load cause the same sympton? Never encountered this issue other then surging on high speed. I think I will put a new plug in just to see. Thanks for the reply

 

[StarTech]

Okay the Nikki is picky about the bowl spaghetti gasket and this particular also uses a separate fuel inlet tube o-ring. The gasket and o-ring has near prefect for them to seal properly which usually means you can't re-use the old gaskets. This especially true since this particular engine appears to have a fuel pump which adds more pressure to system. Also if the main jet is loose in the tube its tiny o-ring would need to replaced too.

I also have seen a few new spaghetti gaskets from Briggs to have defects which why they need to inspected before install with a magnifying glass. Rare but it does happen with these during the manufacturing process.