Small Engines (Lawn Mowers, etc.): Craftsman engine floods/wont start when hot, eager 1 engine, internal passages


Question
Hi John,
I found that you had responded to an identical question on the exact same Craftsman engine (143.006706) four years ago, but the resolution was not posted.

The engine starts fine cold.  Once warm, though, the engine will flood and not start.  I replaced the float needle valve and seat, cleaned the carb, replaced air filter and spark plug which greatly improved engine performance and now the flooding while hot is intermittent (maybe 1 out of 12 times).  As per your advice 4 years ago, I checked the spark when the engine doesn't start and it is fine. Engine does seem to be flooded - you can hear gas gurgling while engine is shut down, spark plug wet with gas, air cleaner wet with gas.  What is pulling so much gas up when engine is hot?

Thanks so much.
Mike

Old post from 2006:

I have a craftsman self propelled 6.75 eager 1/ Engine model 143.006706 / Engine family ytpxs2071ba  and model#917.377690  My problem is when mower is cold it starts right up and runs fine for 10-15 minutes then i shut it off to empty the bag it wont start. if i pull the air filter off it starts on 4or5 pulls. It seems like its flooded, i pull air filter off, after 4or5 pulls i see smoke coming out the muffler and it starts. put the filter back on and it wont start.  ive replaced air filter, spark plug, carb and float assembly, replaced breather tube drained fuel tank. im drawing a blank. can you give me some insight. please!

Answer
Hello Michael:

>>From your Description it Sounds like the Carburetor Needle Valve is Sticking.
>>I Suggest you Remove the Carburetor and Check the Float and make Sure there is Nothing that the Float might Catch on and Inspect the Needle Valve Port for Small Burrs that might Catch the Needle Valve and cause it to Stick.
>>Did you Soak the Carburetor or Use Spray Cleaner?
>>The Following is a Basic File I Made for Cleaning Carburetors. Any Input is Appreciated. Even though the Carburetor Looks Clean, the Internal Passages May be Restricted with Varnish that Gas Causes to Build Up over Time.
>>Spray Cleaners Remove this Varnish in Layers, so Soaking is the Only Sure Way to Remove ALL this Varnish.  
>>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 (if Applicable), Float Pin (if Applicable), Float (if Applicable), Needle Valve.
Remove Any Adjustment Screws that Go Into the Carburetor Body. The Welsh Plugs Do Not have to be Removed.
>>If you are Able to Remove and Disassemble the Carburetor and Keep the Gaskets Intact, then Usually these Gaskets can be Reused. The Only Parts you May Need to Replace is the Needle Valve.
>>The Float Needle Usually is Not Replaced Unless it is Not Operating Properly (the gas flow not shutting off and the carburetor is Flooding). Do Not Remove the Main Nozzle. This is a Pressed Fit and Removal is Not Required for Cleaning. Soaking and Blowing the Carburetor Out After Soaking will Clean the Nozzle.
>>Once Disassembled, 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.
>>Note: **Pay Close Attention to the Adjusting Screws and Remember which Hole the were Removed from. They MUST be Replaced Into the SAME Hole they were Removed from!!!**
>>***(Do Not Use High Pressure Air for the Zama Carburetors, they have Check Valves for the Primer and these are Usually Blown Out of the Carburetor if Not Careful. Allow the Zama Carburetor to Set on a Drip Pan and Dry)***.
>>****All the Carburetor Adjustments are the Same for Lawn Mower and Trimmers. There are Several Location for the Air Mixture Screws. The Idle Air Mixture Screws are Usually Located at the Top of the Carburetor Bowl and the Top of the Carburetor Body.****
>>If the Main Air and Idle Air Mixture Screws are Side by Side on the Side of the Carburetor, then the Idle Air is Nearest the Engine. The Main Jet Air Mixture Screw is Located in the Bottom of the Carburetor Bowl or Beside the Idle Air Screw on the Side of the Carburetor Body.
>>Some of the Older Model Carburetors have the Main Jet Mixture Screw Straight in from the Top of the Carburetor Body (this is Rare anymore). If you have Cleaned the Carburetor (Disassembled and Soaked Overnight in Carburetor Cleaner (I Use Gunk). Then Blow Out the Passages with Compressed Air and Install a New Kit if Required. Now Setting the Air Mixture Screws:  
>>****Turn the Idle Air and Main Air Mixture Screws In Until SNUG **Do Not Jam** Then Reverse Both Screws 1 1/2 Turns. Holding the Throttle Full Open, Start the Engine. Set the Idle Screw so the Engine will Idle (even if a little high) and then Using the Governor Arm (on chainsaws and trimmers use the Trigger) Rev the Engine Up and Down Until and Turn the Main Air Mixture Screw Clockwise Until Proper Revs are Obtained. Occasionally you May have to Turn Counter Clockwise to Achieve the Proper Revs. Now Allow the Engine to Idle. Set the Engine Idle Screw (Not Idle Air) so the Engine will Stay Running if Required. Now Set the Idle Air Mixture Screw so there is No Hesitation when Throttling from Idle to Full Throttle. Reset the Engine Idle if Required.****
>>If This Carburetor has a Single Air Adjustment (Except Tank Mounted 9200 and 100900 Engine Model Carburetors), Use the Section Above that Pertains to Full Throttle RPM Air Mixture Screw and then Adjust the Screw if Required to Eliminate Any Hesitation when Throttling from Idle to Full Throttle.
>>For the 9200 Model Tank Mounted Carburetor Adjust the Air Mixture Screw Full In, then Reverse 1 1/2 Turns. Set the Throttle Lever to Full Throttle and Start the Engine.
>>Now Carefully Use 1 Finger and Open the Throttle Plate and Over Rev the Engine Slightly. If the Engine Over Revs and Does Not Struggle to Over Rev, then the Carburetor is Set. If the Engine Struggles to Over Rev, then Turn the Adjustment Screw In 1/4 Turn and Repeat the Over Rev Test.
>>If you Adjust to 1/2 Turns In and the Engine Still Struggles to Over Rev, then Return the Adjustment Screw to 1 1/2 Turns Out from Snug and Turn the Screw Out 1/4 Turn. Do the Over Rev Test. Continue this Process Until you have the Engine Over Revving without Struggle.
>>By Adjusting the Carburetor on this Style Carburetor Until the Engine Over Revs without Struggle, you have Adjusted the Air Mixture to the Best Possible Setting.
>>This file was Intended to Give you the Basic Carburetor Cleaning Instructions and May Not Reflect Your Carburetor Components.
>>If you have Questions, Please Ask. The links Below Provide Good Directions on Cleaning the Carburetor.  Make sure you use Compressed Air to Blow through all the Carburetor Passages to make sure they are Clear.  
>>1- http://www.repairfaq.org/samnew/lmfaq/lmclctc.htm   
>>2- http://www.cpdonline.com/692509.pdf   .
>>To View a Breakdown of this Unit Go to this Site Addy, http://www.searspartsdirect.com/partsdirect/index.action?sid=PSHx20080114x00001 and Enter the Model Numbers and Click Search. From this Page you can View Diagrams and Parts Lists.
>>If you Hit a Snag or this Does Not Correct the Problem,  I Hope to be Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Be Safe and Happy. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 5 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Comments and Ratings are Greatly Appreciated. Thanks.

Respectfully

John