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Problem w/ Craftsman 46" Kohler 18.5 hp. won't run with choke in?!?!


TBigLug's Avatar
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05-18-08, 02:19 PM   #1  
Problem w/ Craftsman 46" Kohler 18.5 hp. won't run with choke in?!?!

I've got a mid-late 90's Craftsman riding mower. 18.5 hp. Kohler Command V-Twin (Model #: CV18S; Spec. #: 61554; Serial #: 2732102381). Choke the mower, fires right up. Push choke in, mower dies (even after it is warmed up). It has new spark plugs, air filter and fuel filter. Fuel flows fine up to the carb. No matter which way you turn the mixture(?) screw, doesn't effect anything. Will run fine (with the choke halfway out) for a couple minutes, then it will start dying. It will flutter worse and worse over the next couple minutes. Then, just before it dies, you will here a "pop" and it will run great, starting the cycle all over again. I got the mower last year and it's done this ever since I've owned it. An instructor I had, told me it could be something plugging up the jets so I pulled the screw all the way out and shot some carb cleaner into it. Helped a little for a while. Not much. Anybody have any ideas? I'm a pretty accomplished auto mechanic but this small engine stuff seems to elude me. I'd appreciate any input or if anybody has some kind of repair manual that could help me out I'd appreciate it. Thanks.

 
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05-19-08, 12:54 AM   #2  
You'll need to take the carb apart and clean it out inside.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

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05-19-08, 06:20 AM   #3  
Do you know where I can get a gasket kit for it? Thanks.

 
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05-19-08, 11:32 PM   #4  
Most any small engine repair shop should have a kit for it. Take the engine model, spec, and family number to the shop and they can find a kit for it.


"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

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05-20-08, 04:51 AM   #5  
Posted By: TBigLug I've got a mid-late 90's Craftsman riding mower. 18.5 hp. Kohler Command V-Twin (Model #: CV18S; Spec. #: 61554; Serial #: 2732102381). Choke the mower, fires right up. Push choke in, mower dies (even after it is warmed up). It has new spark plugs, air filter and fuel filter. Fuel flows fine up to the carb. No matter which way you turn the mixture(?) screw, doesn't effect anything. Will run fine (with the choke halfway out) for a couple minutes, then it will start dying. It will flutter worse and worse over the next couple minutes. Then, just before it dies, you will here a "pop" and it will run great, starting the cycle all over again. I got the mower last year and it's done this ever since I've owned it. An instructor I had, told me it could be something plugging up the jets so I pulled the screw all the way out and shot some carb cleaner into it. Helped a little for a while. Not much. Anybody have any ideas? I'm a pretty accomplished auto mechanic but this small engine stuff seems to elude me. I'd appreciate any input or if anybody has some kind of repair manual that could help me out I'd appreciate it. Thanks.
You are sucking air into the engine. By the choke being closed it reduces air flow and then after it warms awhile that is causing your other problems the popping is too much gas in the cylinder and either you are experiencing prefire or delayed fire in the cylinder. After you first crank try shooting either carb cleaner or, starting fluid or wd 40 around intake gasket at cylinder head and also carb mounting gasket. This should change the engine RPMS if a gasket is bad. Also try replacing your gas line with clear line and watch to see if any air bubbles are present. You cannot adjust this problem out with the adjustment needle because your air flow is coming in elsewhere. Good Luck Ooops 59

 
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05-20-08, 05:40 PM   #6  
Thanks cheese, I'll do a search on yellowbook for a shop close'ish to me. (LOL, I'm out about 15 miles past the sticks! LOL)

oopsy, I'm gonna give that a shot tomorrow. I had a truck that had a leak in the manifold we used the same method to find that one.

 
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06-05-08, 06:52 AM   #7  
Well, got the kit, went through the whole carb, didn't change a thing. ???????????? I'm going to replace my gas line with clear tubing and my fuel filter next to see if maybe the fuel line swelled and I'm not getting enough flow? Any other ideas? lol

 
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06-06-08, 12:49 AM   #8  
Did you soak the carb in cleaner (a bath type cleaner preferrably), blow out all passages, and verify all jets and passages are clear and open?


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06-06-08, 05:22 AM   #9  
You carburetor needs more/better cleaning. I work on these things everyday and have learned how easy it is not to adequately clean one. As careful as I am, I occasionally will have one that needs additional cleaning.

Having to choke the carburetor to keep it running indicates the idle circuits are most likely blocked or partially blocked. Use small diameter copper wire and run through each passage.

I am only a fan of dipping a carburetor when they are severely dirty. Not that I know better it is just what I prefer. I most often use “Valucraft Carb Cleaner” from my local Auto Zone parts store. If you have an Auto Zone parts store in your town, purchase a can of Part Number: AZ-4, 13 ounces in a yellow and black aerosol can with a red plastic cap. It sells for around $2.00 per can. I have been very successful in cleaning carburetors with this cleaner. I have not had many carburetors I could not clean. Sometimes I use the entire can. At the price it sells for, so what.

WARNING - Do not get “Valucraft Carb Cleaner” in your eyes or on your skin. Use a full-face shield for eye and face protection. Wear protective gloves. The cleaner will damage rubber so remove rubber carburetor parts to prevent damage.

Valucraft Carb Cleaner will melt and wash away varnish. Spray as much cleaner as possible into the fuel passages. Follow up by blowing out with compressed air. Be sure to blow passages and everything else out after cleaning.

Get the service manual for your engine at the Kohler website. The manual illustrates your carburetor very well. Ensure each of the fuel passages are clear, especially the “slow circuits”. Check the float height to manual specifications.

Good luck to you

 
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06-06-08, 05:38 AM   #10  
I completely disassembled my carb, pre cleaned it with the spray, soaked it overnight (minus the plastic parts) resprayed scrubbed and cleared all the passages. I still have all the carb dip brushes and tools from spending years rebuilding holleys. Every passage I found was blown out with carb cleaner and compressed air. I'll go back through it again but I doubt that any passages are plugged up still. Could something outside the carb be having an effect like this? Not enough fuel?

 
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06-06-08, 09:29 PM   #11  
Well, you said fuel flow to the carb was fine in the first post. When it dies, check flow. If there is none or very little, then there's the problem. The fact that you can choke it halfway and make it run well tells me most likely the carb still has a blockage somewhere. Possibly behind the welch plug?


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06-07-08, 07:03 AM   #12  
Fuel pump needs to supply adequate fuel supply. The manual states, minimum fuel delivery rate must be 2 gal./hour with pressure at 0.3 PSI and a fuel lift of 24 inches. A 0.34 gal/hour fuel rate must be maintained at 5 Hz.

Fuel supply line and filter needs to be free flowing.

If the pump and lines are OK and you are satisfied the carburetor is clean, circuits open and float set correctly I see no choice but to replace the carburetor. Ensure the fuel tank cap vent is not restricted also. I guess a limited venting could factor in this.

All this said, my money is with Cheese.

Good luck to you

 
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