Little bit of a read to explain but I want the full picture given. I am a mechanic by trade though never worked professionally on small engines. Please excuse me if I use the wrong terminology.
B&S 22HP 724cc Commercial Zero turn / MFG # 44T677-0003-G1
Mower starts up and runs first try every time (one second of pulling the choke)
Will idle perfectly low or high MOST times. Until it starts acting up, which is only after it has been running for about 10-15 min with blades going as well. Then it surges and tries to stall until the choke is pulled. Then it will run again, or sometimes it dies anyways even with the choke pulled (usually dependent on the position, half pull seems to be a sweet spot). Blades being engaged usually cause it to stall when it starts to act up. I know this usually indicates too much air or lack of fuel issue (lean). She runs like a bat outta h377 even with the blades engaged up until it decides to act up. Still starts right up every time after stalling (still have to use choke for 1 second) Then it will idle no problem again. Engage blades, kaput, pull choke, runs for a few, kaput again. I did ensure no blockages or grass buildup in the blade area. If I let it sit for a while, she'll act right again for another 10-15 min blades or not.
She's older and was inherited so things I have done to ensure a sound machine (within the last month) after she started acting up to help get her back in tip shape.
Plugs are newish so I did not replace them (not an issue as I am getting great spark and the NGKs look great)
New coils / magneto armatures (new from local small engine shop, unsure of brand however they cost just as much as B&S branded. Coils spaced .008-.0010 in away from flywheel at the magnetic portion as instructed in the manual. (spaced with digital caliper tool). Di-electric grease was used.
New air filter, fuel filter, oil filter and oil (fuel filter only thing not B&S branded)
New B&S fuel pump
Took apart the carburetor and cleaned it thoroughly (did not replace and did not look bad inside it, cleaned it anyways)
While I had the carb off, I replaced the needle float because I do know they like to swell and cause a fuel cut off. The new needle as B&S and seemed to be an updated model.
After all this, I thought maybe alternator? I TESTED BUT DID NOT REPLACE the alternator (stator), and at full throttle it spec'd at 26 - 29V. Seems low to me as I expected 30-40V. However I refrained from replacing as my thought process was if I'm being fuel starved, it could cause lower RPM, which in turn means lower voltages.
I'm kinda stuck here unless ya'll think I SHOULD replace the Carb. Up until now I only wanted to do so much as maint. not just throw parts at it due to the fuel filter being BLACK, and I hadn't changed oil since last season. Any advice would be appreciated. I'm sure I'm missing something.
Unless something is lodged in the valve then that isn't the problem. I have seen cases with some of the newer low emission fuel lines where the plastic liner comes loose and will block the fuel line off also. Will usually show as a soft spot in the fuel line if you pinch it with your fingers. Also if the fuel lines have been clamped off with either pliers or a hose clamp can break the inner liner causing issues.
Unless something is lodged in the valve then that isn't the problem. I have seen cases with some of the newer low emission fuel lines where the plastic liner comes loose and will block the fuel line off also. Will usually show as a soft spot in the fuel line if you pinch it with your fingers. Also if the fuel lines have been clamped off with either pliers or a hose clamp can break the inner liner causing issues.
Tank is currently draining. At first it was a slow drizzle coming out (pre cut off), put pressured air through the line UP into the tank and now it's flowing great. Waiting for complete drain and gonna just clean and rinse and pressure wash all of it. Not sure if it's the pressure causing it to flow well or if something was lodged. It's not the cleanest in the tank so highly possible. I'm a little ashamed to not have thought about it, though not usually an issue to think about in vehicles, thus completely skipped my brain . If this is the resolution, I owe you a beer.
Unless something is lodged in the valve then that isn't the problem. I have seen cases with some of the newer low emission fuel lines where the plastic liner comes loose and will block the fuel line off also. Will usually show as a soft spot in the fuel line if you pinch it with your fingers. Also if the fuel lines have been clamped off with either pliers or a hose clamp can break the inner liner causing issues.
So now she's running a whole lot better, didn't even need choke after fuel was running back in the system. I'm gonna replace all the lines due to the fact now if I'm at wide open throttle and moving forward she'll bog down, then I'll stop an sit for a second and she comes right back. I'm assuming a line is collapsing somewhere. They've seen better days anyways.
Replace all the fuel lines/filter as you are doing.
Flush out the fuel tank. Every tank in the world will have some grass and dirt in the bottom. This debris will try to make it's way to the carb and impede fuel flow. That causes bogs and such as you are starving the engine for fuel. Make sure the tank is spotless.
Do a valve inspection yearly for a good running engine.
Clean the block and cooling fins YEARLY or more often. This is in every engine manual as a must-do or you will get engine damage. These are air cooled engines.
If you have room, install a fuel block off valve inline to the carb.
. If this is the resolution, I owe you a beer.