I have a Bolens Riding mower with the 22hp briggs and stratton motor #407777. I had used it a couple times to mow this spring before it started acting up. It doesn't seem to have any power. If i get it to full throttle and engage the blades it starts to stumble and die. I tried disconnecting the kill switch in the seat and didn't help. Here's a list of everything I've done:
Complete carb rebuild
New fuel pump
New fuel lines and filter
New plugs and wires
New coils
Gas tank cleaned out
Fresh gas
Ran with and without air filter
Replaced governor gear
Adjusted the governor arm
Checked and adjusted valve gaps
I even removed the rocker arms and springs so i could put the valve stems in a drill chuck and spin them on the seats to clean them off. (One of the four seemed to have some buildup that smoothed out after spinning it)
I am leaning towards a governor issue since one time i was able to mow with it by disconnecting the governor and wiring it into position. I just had to slow down when i got in the thick grass. But now, after all that, it will start but idles really rough and slow like a Harley motor. Moving the throttle does nothing. Pulling the choke kills it. I took the muffler off to make sure it wasn't clogged and it ran the same. (And really sounded like a Harley then!) If i pull the spark plugs they are both black like it's running really rich. Also there is a little black smoke coming out the exhaust while it's chugging along. So that's where I'm at. Totally stumped. I normally don't have this much trouble fixing something. Which is why I'm here looking for new ideas. I've got way to much money in it to quit. Please help!
I checked that early on. It ran really bad or died when i pulled either plug wire. It runs poorly with both but better than just one. I should also mention that one time after putting back together it ran up full speed and wouldn't slow down. I shut it off, restarted it and old problem was back. Rough idle, no power, no throttle response. Even though it seems like a governor issue, I've checked the entire governor system inside and out and seems to be hooked up right, adjusted right, responding, etc.
#4
Carscw
Check the throttle plate on the carb. It is held on by two little screws sounds like it has came loose.
Look in the carb and move the throttle and see if the plate moves as it should.
Are you talking about the throttle plate inside the carb? I removed and reinstalled that when i rebuilt the carb. That and the choke plate. So i know they are both secure. If you mean something different can you provide a picture?
Are you talking about the throttle plate inside the carb? I removed and reinstalled that when i rebuilt the carb. That and the choke plate. So i know they are both secure. If you mean something different can you provide a picture?
That's what I mean.
Check it anyways.
When you take then screws out and put them back in they like to fall back out.
#7
Rokon
You have replaced almost everything that could be possibly related to your problem. The only thing not mentioned was timing, like a slightly sheared flywheel key.
On a side note, I have cleaned and rebuilt carbs that should have worked fine, but needed to go back in the tank for another cleaning. You mentioned dying under a load once blades are engaged. This opens up a different circuit in the carb. Just thinking out loud...
Well the carb plates are secure. I also pulled the flywheel and the key looked brand new still. Yes the carb has been in the back of my mind. I've thought about buying a whole new one but it's so dang expensive. Maybe i can find a donor motor on craigslist. I'll keep working and give updates soon.
I have the same motor and carb and when i rebuilt my carb i had about the same problem what i found was their is a form bushing on the outside of the carb on the throttle shaft that broke in half and fell off that i didn't notice was gone. I think it helps center the throttle plates in the carb here is a link to the break down of the carb I think it is number 987 Lawn Mower Parts, Small Engine Parts & Much More! | PartsTree.com - Briggs, MTD, Toro, Cub Cadet, Husqvarna, Troy-bilt...hope this might help
UPDATE: I found and installed a brand new carb on craigslist for $60. :thumbsup: When i started it the rpm's would Rev up out of control forcing me to shut it off. Tried to adjust the governor, and same thing. Then upon closer inspection i noticed that the bolt that tightens the governor arm on the shaft was above the shaft instead of below it so it couldn't grip it tight enough, allowing it to slip. I repositioned the bolt and started it up and SUCCESS! I'm pretty sure the new carb fixed it. But still not 100% sure.
Jimmy: i looked for that bushing on the old carb and all that's there is a foam washer. Pretty sure that's what was there when i tore it apart but maybe i had the same problem you had on yours. It does have a slight bit of play in it but not much. I'm half tempted to put the old carb back on to see if that was really the problem.
So, now i have a better problem to fix. The motor changes speed with the throttle like it should and the governor is doing it's job, but the rpm's at full throttle are WAY higher than they use to be. I mowed with it tonight and had to set it at barely half throttle and it was still shooting grass out 20 feet! I found the idle adjustment screw but I'm not sure how to adjust my top end speed. Any ideas? But it's running better and stronger than it ever has. I guess that's what happens when you replace every part imaginable. :biggrin: thanks everyone for the help. Nice to have someone to bounce ideas off of!
