What am I missing, 540cc Briggs and Stratton engine running rich

[Yooper]

I’m going to throw this out there from a similar experience. The issue could be electrical in that it seems to run good cold but comes on with heat, which electricity doesn’t like. The mower I fixed had a corroded ground wire. Start and run fine when cold but after 15 minutes or so it would lose power and sputter. A weak coil could be a possibility also. Good luck!

 

[Joisey]

I had a similar problem on my Husqvarna zero turn with a Kawasaki engine. Thought the carb had junk in it after 20 plus years. Engine would run fine, then load up. Found out the coil was breaking down when it got hot and giving a weak or intermittent spark. Replaced both coils with new Kawasaki parts and the problem went away.

 

[GeoHorn]

Drain the fuel and then try fresh gasoline from a clean can. Previous operator may have given you a problem.

THAT ^^^^ is an EXCELLENT suggestion. BTDT

Bro-in-Law had a mower that he’d retrieved from HIS blood-bro…… after the bro had kept it about 4 yrs.

BIL said it was in perfect shape…but would not start. Asked me to help him figure it out.

Yep. Old gas. Dumped the tank. Fill with fresh fuel. Three pulls later…..VrrrRRRROOOOMMMMMM!

 

[ken erickson]

Old engine, eventually 'rich' even with a different carb is usually oil burning.
If anything, as a carb gets older, it leans out, between buildup on the jets reducing fuel flow and wear on the throttle shaft, letting air in.

I believe I have this engine running correctly at this point. Thanks to all that have offered suggestions !

This post by William1 got me to wondering along with the fact when I ran the tractor for 1/2 hours I was seeing a hint of blueish smoke hanging in the air.

Turns out the head gasket was blown and is a common issue on these Briggs Intek engines. The gasket blows between the cyl at the 3 O'clock position into the push rod galley.

 

[sdodder]

I fix small engines as a side hobby/business for friends and family. I've pretty much stopped buying Amazon carbs. The price is tempting, but they always seem to not quite fix the issue. It also seems like you get 1 good one for every 4 bad ones. I'd try rebuilding the OEM one or buy a new OEM carb. My guess is that on both the old one and this current Amazon carb the fuel needle isn't seating right and allowing the carb to run rich, especially if jostling over rough ground causes it to puff black smoke.

Good morning- interesting comment about replacement carbs. I fix a lot of small engine stuff as my "retirement hobby" I myself usually TRY to rebuild the original carb, but I've always been tempted to try one of the amazon ones- This info is good to have Thanks, Steve

 

[ken erickson]

Good morning- interesting comment about replacement carbs. I fix a lot of small engine stuff as my "retirement hobby" I myself usually TRY to rebuild the original carb, but I've always been tempted to try one of the amazon ones- This info is good to have Thanks, Steve

I am going to keep the OEM Nikki carb and pick up the rebuild kit for it as a spare. I prob got lucky on the Amazon one. I watched a few small engine Youtube channels where they mentioned that about 1 in 4 of these really inexpensive clone carbs work!

I picked this riding mower up in a trade with my long time neighbor that sold his house and moved into a apartment. He will be turning 90 this year and downsized. I had no cash invested in it, traded for storage space in my storage shed. I will be taking this one down to my land and using it a few times a year in my camping area etc.