Hi all, I've got a Briggs 3.5hp, model 91202, made July 1992 with a Pulsa Jet Carb. I'm chasing a running rich issue and wondering if anyone can think of something I might be missing. I did a full carby clean including idle circuit, new gaskets, diaphragm and spring. It is running rich on both idle and higher speeds. It only has the one mix screw for the idle circuit, no high speed mix screw. Idle mix screw is set at 1 1/2 turns out from bottomed out. It runs fine, but puffs some black smoke on idle and higher revs. Less on higher revs. I'm sure I got all the airways clean and it's not the air filter, that's new and removing it makes no difference. Only thing I can think is maybe the new diaphragm has a pinhole in it and is letting fuel in to the carb throat. I did originally see a little fuel around the outside of the diaphragm cover after replacing the old one, so took it off and reseated it and it appears to have stopped I think but hard to see in the failing light I was in.. I've got a new diaphragm in the mail to try but failing that, any advice/ideas on how else the mix could be rich at all speeds in relation to the carby? Anything I could look for that I haven't thought of? I believe there could be other causes related to timing or possibly a valve but am trying to rule the carb out before I go further down that path. Thanks for any advice.
Cheers
Last edited by Andy E; 08/03/21 05:19 PM.
