Questionhello sir, I have a 4.0 Craftsman20" rear disharge rotary lawn mower, model no. 917.389250. It has been sitting outside uncovered for a year un-used. I decided to fire it up, well no go. I changed the oil, put in fresh gas, new spark plug. I tried to fire it up and get nothing, the flywheel spins with no fire. I removed the air filter and sprayed starter fluid in the carb and it only backfired from the carb and still did not start. The engines model number is 143.994022. Thank you for your time and look forward to hearing from you.
AnswerHello Travis:
>>The Carburetor May Require Soaking and Cleaning, the Ign Module Shut Off Terminal (shut off Switch) May Require Cleaning or the Ign Module is Bad and Requires Replacing.
>>1- Remove the Blower Housing (metal engine Cover) and Remove the Ign Module/Coil. Make Sure the Magnets and the Coil/Ign Module Pick Ups are Clean and there is No Rust Between the Magnets and Ign Module/Coil Pick Up.
Locate the Shut Off Switch at the Control Bracket and Make sure it is Clean and Not Grounding Out the Ign Module/Coil.
>>The Following is a Basic Instruction File I Made for Checking the Coil/Ign Coil/Magnetron/Armature on Small Engines. Any Input is Appreciated.
>>**To Check the Ign Coil; Remove the Spark Plug/s.
>>With a Good Plug, Wrap a Wire Around the Threads of the Plug and Attach the Other End of the Wire to the Engine Block. Check for Spark. If No Spark, then
>>Remove the Blower Housing (metal engine cover). The Wire that is Connected to the Coil/Ign Module from the Shut Off Switch needs to be Removed (unplugged) from the Coil/Ign Module.
>>Now Check for Spark at the Plug.
>>If Spark, then the Shut Off Switch or the Wire is Bad.
>>If Still No Spark, then the Coil/Ign Module is Bad. If there are Safety Switches on this Unit and the Coil is Good; you Need to Check the Safety Switches for Being Bad and Check the Oil Guard Switch also.**
>>***Anytime a Magnet that is Set to the Correct Distance from the Armature/Ign Coil Pickups, the Armature/Ign Coil will Fire the Plug if it is Good. The Armature/Ign Coil Gap should be .020in between the Flywheel and the Armature/Ign Coil Pickups. You can Use a Side Panel from a Drink Carton (Mt Dew, Pepsi, ect) and Place it Between the Flywheel and the Armature/Ign Coil. Allow the Magnets on the Flywheel to Pull the Armature/Ign Coil Together and then Tighten the Armature/Ign Coil Bolts. Carefully Turn the Engine while Pulling the Cardboard Out from between the Armature/Ign Coil Pickups. The Armature/Ign Coil is Now Properly Set.***
>>The Following is a Simple Way to make Sure the Engine is Getting Gas from the Carburetor to Run.
>>Pour a Small Amount of Gas (approximately 1/4oz) into the Carburetor Throat and Try to Start the Engine.
>>If the Engine Starts and Quits, then Check the Carburetor Solenoid.
>>If the Carburetor Solenoid is Good or has been Removed and the Engine will Start and Quit when the Gas is Poured into the Carburetor Throat, then Soak and Clean the Carburetor.
>>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 Welch 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.
>>***(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. Turn the Main Air Mixture Screw Clockwise Until Proper Revs are Obtained. Occasionally you May have to Turn this 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 above Provide Good Directions on Cleaning the Carburetor. Make sure you use an 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 .
>>If you Hit a Snag or this Does Not Correct the Problem, I am 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
