Can't get mower to run right

peabodyn · Jun 16, 2016

I have a 12A-18M7002 MTD Yard Man Self Propelled 173cc OHV mower.

This model has the Kohler engine.

It is difficult to start but will eventually start and run terribly.

It spits and sputters.

I have:

Changed the spark plug
Drained the gas, cleaned out the tank and used new gas
Took the original carburetor off and cleaned all the passages.
Swapped the carburetor for a known working one.
Checked the muffler to ensure it wasn't clogged.

The automatic choke works as I see it adjusting the carburetor as the motor tries to stabilize itself.

The coil must have spark as the engine does start, but runs terribly.

I don't want to throw a new carburetor or coil at it without knowing what is wrong.

There were a couple of times that it actually started easily and ran fine, but the symptoms have recurred.

Any ideas?

Thanks

mechanic mark · Jun 16, 2016

http://www.mtdproducts.com/equipmen...Code=03&modelNumber=12A-18M7002&serialNumber=

See pages 18 & 25 in engine operators manual for troubleshooting chart & fuel filter location. Carburetors are different, specific carburetor part number for specific engine model number to run properly. You may want to purchase a carburetor rebuild kit by looking in parts manual for your engine model parts list.

peabodyn · Jun 16, 2016

mechanic mark said:
http://www.mtdproducts.com/equipmen...Code=03&modelNumber=12A-18M7002&serialNumber=

See pages 18 & 25 in engine operators manual for troubleshooting chart & fuel filter location. Carburetors are different, specific carburetor part number for specific engine model number to run properly. You may want to purchase a carburetor rebuild kit by looking in parts manual for your engine model parts list.

Thanks, I did check the troubleshooting chart and even removed the fuel filter to ensure that gas was flowing. So far no change.

I suspect the carburetor is defective, I have had it apart 2x but there must be an issue with it.

Am going to order a new carburetor.

Lawnaholic · Jun 16, 2016

peabodyn said:
Thanks, I did check the troubleshooting chart and even removed the fuel filter to ensure that gas was flowing. So far no change.

I suspect the carburetor is defective, I have had it apart 2x but there must be an issue with it.

Am going to order a new carburetor.

I know this might be a long shot, but have you checked the air filter? I have a MTD Black push mower (MTD engine) and it has been running rough as well. I've cleaned the filter, but will not know when this may have fixed the issue, until my next grass cut.

Hopefully this can steer you some direction...

peabodyn · Jun 16, 2016

Lawnaholic said:
I know this might be a long shot, but have you checked the air filter? I have a MTD Black push mower (MTD engine) and it has been running rough as well. I've cleaned the filter, but will not know when this may have fixed the issue, until my next grass cut.

Hopefully this can steer you some direction...

Actually, the air filter is clean - good idea though.

I did see a video on Youtube that suggested adjusting the idle speed and potentially drilling the low idle jet to a slightly larger diameter.

I believe that the prior owner of this mower messed with it and sold it because he couldn't fix it.

I got it real cheap - now I'm paying for it in time and potentially parts.

Lawnaholic · Jun 16, 2016

peabodyn said:
Actually, the air filter is clean - good idea though.

I did see a video on Youtube that suggested adjusting the idle speed and potentially drilling the low idle jet to a slightly larger diameter.

I believe that the prior owner of this mower messed with it and sold it because he couldn't fix it.

I got it real cheap - now I'm paying for it in time and potentially parts.

I adjusted my idle screw to allow the mower to run a little louder, but it kept my mower from dying every 15 seconds. I'm hoping the air filter is clean enough so I can adjust it back.

Update here when you find a fix!

--Nick

hdsport · Jun 17, 2016

Is there a diaphragm that you could replace?
Ethanol Gas has been a cause of the degradation of many, many of these.
I have replaced about a dozen of the diaphragms in various yard motors in the last year.

Advise as able.
Thanks.

peabodyn · Jun 17, 2016

hdsport said:
Is there a diaphragm that you could replace?
Ethanol Gas has been a cause of the degradation of many, many of these.
I have replaced about a dozen of the diaphragms in various yard motors in the last year.

Advise as able.
Thanks.

Don't think so. I've checked the schematic diagram and there isn't a diaphragm.

Marty013 · Jun 17, 2016

have you checked the ignition switch? ( whatever eletrical contacts that move when you pull the bail-bar down) it might be the problem... you seem to have eliminated the possibility of fuel issue very well and hat the few plces an ignition problem could occur with a cold engine i think.. other possibiility is an air leak ( head gasket, intake manifold gaskets)

when it does start.. does it smoke black smoke?

peabodyn · Jun 20, 2016

I've found out that if I manipulate the lever on the carb (closest to the engine), I can get the mower to run fine.

I suspect the prior owner messed with the carb and put it back together the wrong way.

I have a similar carb and will compare the two to see if I can see what's wrong.

Can't get mower to run right

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