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12 HP Flat Head Running Rough.

#1

LaWn GuY

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.


#2

A

activelife92

LaWn GuY said:
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.
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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.


#3

LaWn GuY

LaWn GuY

activelife92 said:
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.
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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??


#4

A

activelife92

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


#5

reynoldston

reynoldston

LaWn GuY said:
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??
Click to expand...

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.


#6

T

Tinkerer200

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

Walt Conner


#7

reynoldston

reynoldston

Tinkerer200 said:
Sounds like a good possibility of water in carb float bowl.

Walt Conner
Click to expand...

Very possible, might try some dry gas?


#8

LaWn GuY

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???
Carb1.jpg


#9

T

Tinkerer200

LaWn GuY said:
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
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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


#10

LaWn GuY

LaWn GuY

Tinkerer200 said:
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
Click to expand...

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.


#11

T

Tinkerer200

"Or maybe link a youtube vid If u can thanks."

I don't do U-tube, Service Manual should have all you need.

Walt Conner


#12

LaWn GuY

LaWn GuY

Turns out It Is a owners manual so can u link me a service manual please. Model Number 281707 Type 0412. Also It starts and stalls unless I keep turning the choke on and off. leemankeith@yahoo.com


#13

icon2000

icon2000

Im told those engines are tough in have the 12.5 in my rider so good so far. Hope you figure it out.


#14

LaWn GuY

LaWn GuY

icon2000 said:
Im told those engines are tough in have the 12.5 in my rider so good so far. Hope you figure it out.
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Do u mean tough like they need everything perfect or do u mean they can take alot of abuse??? I took the Carburetor completely off and cleaned It with cleaner, and put everything back but the choke linkage came off from the engine linkage and Im not sure I put It back on right. The choke will close fully when I turn the choke on but when I turn It off the butterfly doesn't open all the way just opens a little. I don't know If It supposed to open all the way or not.


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