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Discussion Starter #1
Good morning. I just bought a pro 12 which the kohler engine. It runs ok but it wants to die if you dont choke it. I know that it sat for a while before I bought it so I think the carb must be gummed up a bit. I have replaced all the fuel line and fuel filter and also the spark plug but the issue remains. From digging around on this great site I discovered that I have either a Kohler card or a Walbro. I have a couple of pics and maybe someone can look and tell me which one I have. I also saw a few posts saying that these are releativly easy to clean without even removing from the mower. I do not know where to start here so I was wondering if someone could give me some pointers. The service manual talks about cleaning but that is with the carb off.
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Thanks for all the help
 

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Sorry not a gravely guy so not sure which carb. Sometimes if they will only run on choke may mean the fuel line isn't delivering enough fuel. Check the tank and see if there is sediment in it that is clogging a screen on the fuel line. Those are gravity fed so would be on bottom of tank and be a screen of some type to keep crud from passing into the line. Probably not a bad idea to clean the tank and replace the line to the carb. Good luck!
 

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Sorry not a gravely guy so not sure which carb. Sometimes if they will only run on choke may mean the fuel line isn't delivering enough fuel. Check the tank and see if there is sediment in it that is clogging a screen on the fuel line. Those are gravity fed so would be on bottom of tank and be a screen of some type to keep crud from passing into the line. Probably not a bad idea to clean the tank and replace the line to the carb. Good luck!
On these tractors, the fuel screen is built-in to the petcock assembly. I like to replace them as a matter of course when replacing fuel line with a new to me machine as they are cheap and often leak in the full open position. Check that it turns easily and is open with no leaks.

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Looks like a Walbro.

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Discussion Starter #5
thanks for the feedback. The petcock does not lea when fully open and turns easily. Maybe I should replace anyway, do you know the part number so I can order one. Also any idea on dissembling teh carb while still on the machine or is what I have heard just nonsense.
 

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Some folks drop the bowl, remove the jets and use compressed air with the carb still on the tractor, but this not a cleaning and I don't do it. If dropping and cleaning the bowl doesn't buy me anything, I remove and run it through the ultrasonic cleaner. If no improvement, i disassemble and run through the ultrasonic cleaner again and rebuild it with a kit.

gravely_tractor_museum on Ebay sells the fuel petcocks.

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I'd probably lightly touch the points with either a fine grit sandpaper or points file.

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Discussion Starter #9
If I change teh fuel petcock do I need to put thread tape on the petcock when I thread into the tank or not ?
 

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Having to run on partial, or full choke usually means a clogged carburetor. Removing the carburetor isn't difficult (2 bolts, and detaching from the linkage). Doing so would also give you the best access to areas of the carb that could be clogged up. Putting it back together would also be easier, especially the fuel bowl needle, float, and the bowl, and it's o ring (much easier putting them back with the carb upside down than right side up, and mounted to the engine).

To clean, you would remove the fuel bowl, the float, and float needle, and the high, and low speed adjustment needles.
Then spray into, and through all of the openings with spray carb. cleaner, using the straw. Spraying into one opening, you will see the spray exit the carb. though another opening. Also, the "high" needle shaft has a few tiny (barely visible) holes in it's shaft. Butting the end of the straw up to one of them, hold the needle away, and briefly shoot the carb. cleaner into the hole. Look for spray to exit the other holes.

Counting the revolutions as you unscrew the needles, and counting them again when you replace them will help return them to their pre removal adjustment.
 

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Personally, I would advise against pipe tape. It can unravel and get into your carburetor (ask me how I know). Now, I'm not sure how resistant pipe dope is to gasoline. I don't think I put anything on the shutoff valve I put on my L model, and it doesn't leak.
 

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Having to run on partial, or full choke usually means a clogged carburetor. Removing the carburetor isn't difficult (2 bolts, and detaching from the linkage). Doing so would also give you the best access to areas of the carb that could be clogged up. Putting it back together would also be easier, especially the fuel bowl needle, float, and the bowl, and it's o ring (much easier putting them back with the carb upside down than right side up, and mounted to the engine).

To clean, you would remove the fuel bowl, the float, and float needle, and the high, and low speed adjustment needles.
Then spray into, and through all of the openings with spray carb. cleaner, using the straw. Spraying into one opening, you will see the spray exit the carb. though another opening. Also, the "high" needle shaft has a few tiny (barely visible) holes in it's shaft. Butting the end of the straw up to one of them, hold the needle away, and briefly shoot the carb. cleaner into the hole. Look for spray to exit the other holes.

Counting the revolutions as you unscrew the needles, and counting them again when you replace them will help return them to their pre removal adjustment.
Please allow me to offer a slightly different method for the needles. Screw them in while counting the turns and then take them out. When you put them back in you just screw in until they seat and then you know how much to back them out.
 

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I have another method I have been using. Even with taking the carb and apart and cleaning it, I still run into the same situation you have, it will run with the choke half on, not with it off or it runs lousy with it off. After messing with several generators that have sit around where I work, I have found a way to get a carb cleaned out IF you can get it to run. Mix about 50% Seafoam and fuel and put that in the tank. Then get it started and running however you can do it. Let it run up to 30 minutes or so. You will find after it runs a little bit, it will start running lousy. Take some choke out of it. If it runs a little better, than means the Seafoam is working. Keep running it, you will eventually find the Seafoam cleans it out and you can run it without the choke.
 

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It's probably a carb issue. I had the same thing a few years ago,, and it was due to the carb bolts being loose.
 

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Discussion Starter #15
It occurred to me that maybe I am just trying to turn choke off too soon. How long after starting should be able to shut off the choke and just let it run. It's about 50 degrees where I am.
 

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On my pro 12, I need to turn back to choke halfway as soon as it starts to fire up. Then turn it full off after 15-60 seconds, depending on how cold it is.
 

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Just thinking, you may want to try adjusting the carburetor. Maybe it's just not getting enough fuel. I might try adjusting both needles outward about a quarter turn for starters. The upper needle is the low (idle) adjustment, and the lower needle (close to the fuel bowl) is the high (run) adjustment.
 

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Discussion Starter #18
Just thinking, you may want to try adjusting the carburetor. Maybe it's just not getting enough fuel. I might try adjusting both needles outward about a quarter turn for starters. The upper needle is the low (idle) adjustment, and the lower needle (close to the fuel bowl) is the high (run) adjustment.
I will try adjusting the needles, what is the the third screw for. That is the one in the middle in my picture at the top. Thanks for all your help
 

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The "screw" in the middle is the low speed mixture needle. The horizontal screw at the very top is only for idle speed adjustment. I would give both high (bottom side, near the fuel bowl), and low mixture adjustment needles about a quarter turn outward (unscrew) before starting the engine to give it a chance to run on it's own without the choke, and then adjust them from there.
 

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All good info but I like to completely remove the carb and soak it in a carb "dip", available in gallon cans at a real auto parts store. Depending on how messed up the carb is leave in the dip for at least 24 hours and up to 48 hours. Then wash everything in hot water and force dry using compressed air and a hot air blow dryer if you have one. You have to strip the carb right down to its basic parts but don't put anything fiber or plastic into the dip or you will never see it again.
It is amazing how small some of the ports and passages are in these carburetors, especially in the idle circuit. All of these have to be clear and free or the carb will never work right.

You can thank our federal government for requiring that we use high content ethanol gasoline (mandated subsidy at our expense for the giant factory farms in the mid-West) for these types of problems. If you can find non-ethanol gas close by I suggest you use it for all of your small engines. Have used race gas with oil mix in my two stroke engines for the last 5-6 years with no problems to date, even if they sit idle for 8-12 months.
Good luck
 
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