QuestionQUESTION: I have a 42" Sears Craftsman riding lawnmower with a 16.5 HP B&S motor. The part number of the lawnmower is 917.271634. The engine starts and runs fine as long as I leave it on the slowest speed. As soon as I move the throttle to full in a quick swift motion, it begins to sputter and sounds like it is flooding out. I have cleaned and rebuilt the carburetor but that does not seem to have helped. One thing I noticed when the problem happens is that there appears to be a vertical lever attached to the throttle assembly that moves from a vertical position to leaning forward (towards the front of the mower) when this happens. Go here for some photos:
http://i92.photobucket.com/albums/l14/meyousikmann/100_3561.jpg
http://i92.photobucket.com/albums/l14/meyousikmann/100_3557.jpg
http://i92.photobucket.com/albums/l14/meyousikmann/100_3553.jpg
The lever in the photo will move foward and start to bounce back and forth while the engine is sputtering. The interesting thing is that if I move the throttle lever very slowly, the engine will run up to speed just fine and the lever noted in the photos stays in the vertical position. But, if I move the throttle lever up to speed in one swift motion, or even if I start to move the tractor under its own power after moving the lever slowly, that lever seems to take the inertia and jerk foward where the engine begins to sputter and flood out again. That lever seems to be attached to a flapper on the inside of the carburetor, but it is not the choke flapper so I am not sure what its purpose is. I know this is confusing, but I don't know how better to explain the problem. Please let me know what other information I can provide that will help describe the problem better.
ANSWER: Hello Michael:
The Arm you are Asking About is the Governor Arm. It is Supposed to Move the Throttle Valve Shaft in the Carburetor. From your Description, it Sounds like the Main Jet in the Carburetor is Clogged. Did you Soak the Carburetor Overnight in Carburetor Cleaner? If No, then the Carburetor can Still be the Cause for this Problem. Remove, Disassemble and Soak the Carburetor Overnight in Carburetor Cleaner (I Use Gunk). I have Found that Most People can Use a Breakdown/IPL and Disassemble the Carburetor Enough for Proper Cleaning. You Only have to Remove the Bowl, Float Pin, Float and Needle Valve and Any Adjustment Screws that Go Into the Carburetor Body. The Welch Plugs Do Not have to be Removed. Then Soak the Carburetor Body and Parts in a 1 Gallon Can of Gunk Carburetor Cleaner Overnight. The Can has a Parts Tray Inside it for the Small Parts. Once the Carburetor and Parts are in the Cleaner, you can Replace the Lid for Safety and to Prevent Accidental Spillage. Then Blow Out the Passages with Compressed Air. Install New Parts if Required. Hope this Helps. I am Here if You Require More Assistance. Let me Know What Happens, Please. Thanks.
Good Luck
Respectfully
John
PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 9pm EST (US). My New Day Starts then. Thanks.
Respectfully
John
---------- FOLLOW-UP ----------
QUESTION: Ok. I removed the carburetor and removed the float bowl with the float. I did not remove anything else from the carburetor but simply placed the carburetor and disassembled float bowl and float into the cleaner over night. The next day I rinsed with water, reassembled, and tested. Same result. One other thing to note....as mentioned earlier I can get the engine up to operating speed by moving the throttle lever ever so slowly until it is up to speed. It will continue to run fine like that until I put a load on the engine by engaging the blades or putting the mower into gear and trying to move it under its own power. As soon as I do either, it begins to sputter again and dies. Three questions......First, is it possible that it is still the carburetor since I didn't disassemble it entirely when I soaked it. Second, is it possible that it is still the carburetor since I didn't blow it out with compressed air? Third, the reason I didn't remove the needle valves is because one of them has a black plastic cap over the top of it. It doesn't seem to be just a "snap in place" type cap because I tried to lightly pry it off and it didn't want to budge. I am afraid if I pry any harder, the plastic cap will break. I can't see any other method to remove the needle valve and I don't know how to remove the black plastic cap. Any further suggestions?
AnswerHello Again Michael:
Before we Go Back to the Carburetor; Lets Check the Valve Settings. It is Simple. I Do Not Use the Setting Called for by the OEMs. I have Found that the Following Works Best. Remove the Valve Cover (on the Dead Cylinder for Twin Cylinder Engines). Set the Cylinder you are Setting the Valves on to Top Dead Center (Both Rocker Arms will have Play in them when the Engine is at TDC) When Setting the Valve Clearance. Now Loosen the Valve Adjuster Locks and Set the Intake Valve Clearance to .003in -.005in and the Exhaust to .008in - .010in. I have had Better Performance Out of the Mowers and Less Burnt Valves Using these Settings. If the Valve are Set Correctly, then Break the Plastic Cap. It is an Adjustment Restrictor. It Allows the Owner to Only Adjust so Much, then a Mechanic Will Break it and Remove it for the Cleaning Process and Replace the Cap. If you Did Not Blow Out the Passages with Compressed Air, the the Internal Passages can Still be Restricted. Until the Carburetor is Cleaned and the Passages Blown Out with Compressed Air, the Carburetor will be a Possible Cause. Hope this Helps. I am Here if You Require More Assistance. Let me Know What Happens, Please. Thanks.
Good Luck
Respectfully
John
PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 9pm EST (US). My New Day Starts then. Thanks.
Respectfully
John
