12 HP Flat Head Running Rough.

[LaWn GuY]

What the title says It's running rough and backfires sometime, and will act like It's going to stall but revs It's self back up. Also when I tried to start It this morning It started then ran rough for a few second's and stalled would not start unless I put the choke on, and would stall If I didn't play with the throttle. When It was about to stall I had to put the choke on or It would have stalled. I let zit run In the garage for over a half-hour and It didn't stall once but was still running rough and occasional backfire. Also It will run with the choke on for about 15 seconds then start to conk out. In the mean time I have to replace the starter pinion gear since that's chewed up.

 

[activelife92]

What the title says It's running rough and backfires sometime, and will act like It's going to stall but revs It's self back up. Also when I tried to start It this morning It started then ran rough for a few second's and stalled would not start unless I put the choke on, and would stall If I didn't play with the throttle. When It was about to stall I had to put the choke on or It would have stalled. I let zit run In the garage for over a half-hour and It didn't stall once but was still running rough and occasional backfire. Also It will run with the choke on for about 15 seconds then start to conk out. In the mean time I have to replace the starter pinion gear since that's chewed up.

What have you tried as far as troubleshooting thus far? I typically go down the list to rule out everything I can when tracing an issue. Is the carb clean/good? How's the spark, plug and ignition? I had a broken flywheel key a few years ago that caused the mower to backfire. Timing was off. Since you're having issues that seem to be related to the choke/throttle, I'd start in the carburetor. Take it apart, clean any dirt with carb cleaner, check the seals, seat, float, etc.

 

[LaWn GuY]

What have you tried as far as troubleshooting thus far? I typically go down the list to rule out everything I can when tracing an issue. Is the carb clean/good? How's the spark, plug and ignition? I had a broken flywheel key a few years ago that caused the mower to backfire. Timing was off. Since you're having issues that seem to be related to the choke/throttle, I'd start in the carburetor. Take it apart, clean any dirt with carb cleaner, check the seals, seat, float, etc.

The shop put this engine In, In place of my 13 HP Tecumseh engine so I don't know about the maintenance on It. To me It doesn't look to good It's dirty and look's like It was left out side for awhile. My plans are to replace the spark plug, replace air filter looks extremely dirty and replace fuel filter. I let the old gas run out It and put some fresh gas In. To see If It's the air filter causing the roughness can I run It without the air filter just to trouble shoot it??

 

[activelife92]

Yeah, as long as it's not sucking anything in. I do that to mine on the driveway when troubleshooting.

 

[reynoldston]

The shop put this engine In, In place of my 13 HP Tecumseh engine so I don't know about the maintenance on It. To me It doesn't look to good It's dirty and look's like It was left out side for awhile. My plans are to replace the spark plug, replace air filter looks extremely dirty and replace fuel filter. I let the old gas run out It and put some fresh gas In. To see If It's the air filter causing the roughness can I run It without the air filter just to trouble shoot it??

Very good idea. Always start with the small cheaper things first, all filters, spark plug and fresh fuel. Another thing to add to that list would be to adjust the carburetor. If it still runs that way after said work, you might try cleaning the carburetor, next check valve adjustment.

 

[Tinkerer200]

Sounds like a good possibility of water in carb float bowl.

Walt Conner

 

[reynoldston]

Sounds like a good possibility of water in carb float bowl.

Walt Conner

Very possible, might try some dry gas?

 

[LaWn GuY]

Ok took some pics of the Carburetor there's also some oil on the air filter (and yes the air filter Is removed for testing purposes) and how do u remove the float bowl to clean It out???

 

[Tinkerer200]

Ok took some pics of the Carburetor there's also some oil on the air filter (and yes the air filter Is removed for testing purposes) and how do u remove the float bowl to clean It out???
View attachment 26601

Well that is an old timer. Unscrew the packing nut in the bottom of the float bowl. Be careful with gasket. I can send you a Service Manual for your engine IF you like, address below, put in proper format and remind me engine model number and what you want. You are lucky, you do know you can adjust that carb. That needle in the bottom of float bowl for high speed, there will be a small adjustment screw in the upper side OR top of the carb for idle mixture adjustment.

Walt Conner
wconner5 at frontier dot com

 

[LaWn GuY]

Well that is an old timer. Unscrew the packing nut in the bottom of the float bowl. Be careful with gasket. I can send you a Service Manual for your engine IF you like, address below, put in proper format and remind me engine model number and what you want. You are lucky, you do know you can adjust that carb. That needle in the bottom of float bowl for high speed, there will be a small adjustment screw in the upper side OR top of the carb for idle mixture adjustment.

Walt Conner
wconner5 at frontier dot com

Thanks but I already downloaded one. I just need to know how to remove the float bowl and clean the carb out, sorry If u already said how but Im young and It will be my luck I take It apart nd can't get back together :laughing:. Or maybe link a youtube vid If u can thanks.