QuestionQUESTION: I can't get it to start. Removed air filter,OK, removed carb bowl and cleaned with carb clnr. Removed spark plug, has spark. Don't know what to try next. Looks like the choke is always open, spring loaded so I guess it supposed to be. lost and my grass is growing.
ANSWER: Hello Jim:
>>Here is a Basic Instruction File I am in the Process of Making. It will Might Say Mower, but a Snow Thrower/Blower is Powered by the Same Type of Engine, so the Diagnostics are Basically the Same. >>***Here are some Diagnostic Instructions to Do on the Engine to Locate the Cause/Cure for a Hard/Not Starting Engine. This Does Not Include a Problem with the Valves. If I Suspected the Valves are Involved, then a Separate File for the Valves will be in this E-mail. This is a File in the Making, so Any Input is Appreciated.
>>1- Check the Spark. If Not Firing, then Replace the Plug.
>>2- If the Plug is Firing, then First, Pour a Small Amount of Gas (1oz) Into the Carburetor Throat with the Throttle at Full. With the Throttle Still at Full, Try to Start the Engine. If the Engine Starts and Quits, then Make Sure the Gas is Free Flowing to the Carburetor. If the Gas is Free Flowing, then 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.
>>3- If No Fire at the Plug, then Remove the Coil Shut Off Wire from the Kill Switch at the Engine Stop/Brake Bracket (where the End of the Stop/Brake Cable Attaches at the Engine). Check for Fire. If No Fire, then Remove the Blower Housing and Remove the Ground Wire from the Coil. Check for Fire. If Still No Fire, then the Coil is Bad. *On Some JD Model Mower the Engines Use an Igniter. Remove the Igniter and Coil and have your Local JD Dealer Test them for you.
>>* **On Models with Point Set, the Condenser is Bad and the Point Set and Condenser should be Replaced as a Unit. Make Sure the Point Set Plunger is Fully Extended when Setting the Point Set Gap to .020in.
>>** If there was No Response from the Engine When the Gas was Poured Into the Carburetor Throat and the Plug was Firing, then Check the Compression. If the Compression is Good, the Carburetor has Been Soaked and Cleaned and the Plug is Firing, then Check the Flywheel Key. If the Key is Damaged, then the Plug Firing is Incorrect to the Position of the Piston During the Compression (Power Stroke).
>>*** On the OHV and Some L-Head (Flat Head) Engines there is a Compression Release. The Exhaust Valve Clearance has to be Opened to .020in for the Compression Release Not to Operate; in Order to get a Correct Compression Reading.***
>>Send me the Make, Model and Type or Spec Numbers Off the Engine, Please. With these I can Locate the Proper Manual and Better Assist you.
>>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 10 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
---------- FOLLOW-UP ----------
QUESTION: I've tryed it all. I pulled the top to check the flywheel key and it looked ok. Getting spark. poured som gas behind spark plug. Nothing works. It souds like it wants to bu nothing. Craftsman 6.75 hp model 917.377610 engine model 143.986706 Appreciate your help. God Bless I've even prayed for it.
AnswerHello Again Jim:
>>You can View a Breakdown/IPL of the Engine at this Site Addy; http://www.briggsandstratton.com/maint_repair/manual_and_more/doclist.aspx?categ and Enter the Model Numbers (XXXXXX) and the First 4 Type Numbers (XXXX) in the Appropriate Boxes and Click GO. Then Select Download PDF.
>>What is the Compression?
>>From your Further Description it Sounds like the Compression is Low.
>>This is Usually Caused by the Valve Clearance Requiring Setting, Lapping or Worn Out Compression Rings.
>>I Suggest you Remove the Cylinder Head and Valves.
>>Lap/Seat the Valves First.
>>This Web Page; http://www.affordablegokarts.com/va
lve-lapping.php has a Fairly Good Description and Instructions on Valve Lapping and a Good Explanation of what to Look for when Seating the Valves.
>>The Following is a Basic Instruction File for Setting the Valve Clearances on Non OHV Engines. If you Provided me with the Correct Make and Model of the Engine then the Specifications are Included. If Not I May be Able to Provide the Specifications if you Supply me the Make and Model Numbers.
>>The Most Common Clearances are Listed for this Engine in the Following File. Thanks. Any Input is Appreciated.
>>On this Model Engine I Usually Suggest Reseating the Valves if the Valve Clearance Requires Adjusting.
>>**Remove the Carburetor and the Crankcase Breather/Vent and the Valve (Stem) Cover so you have Access to the Valve Stems, Springs and Keepers.
>>Set 1 Cylinder (on Twin Cylinder Engines) to TDC on the Compression Stroke. Using a Blade Style Feeler Gauge, Check the Clearances. The Intake should be .005in - .007in and Exhaust .008in - .010in. If the Feeler Gauge will Not Slide Between the Valve Tip and the Tappet, then you Must Reset the Clearances.
>>**You Will Require a Small Engine Valve Spring Compressor to Remove the Springs and Keepers from the Valve Stems.** Some Engines Use a Valve Keeper that is like Automotive Keepers (2 Cone Shaped Keepers that Set in the Valve Retainer/Rotocoil Assembly)and the Other Style is a Slotted Retainer that is Moved (once the Valve Spring is Compressed) to the Larger Opening in the Retainer and the Retainer Slips Over the Valve Stem Tip for the Valve to be Removed.
>>Remove the Heads.
>>Set 1 Cylinder so the Piston is at TDC on the Compression Stroke And Check the Clearances Between the Valve Stem Tip and the Tappet. The Clearances are as Follows: Intake Valve Clearance is .005in - .007in and the Exhaust is .008in - .010in.
>>You have to Lightly Grind the Valve Stem Tip and Place the Valve Back Into the Engine (you can Hold the Valve Seated by Hand) and Check the Clearance Until you Reach the Required Clearances.
>>**++** For this Engine Model I Suggest you Reseat the Valves while you are Setting the Correct Valve Clearance. For this you will Need a Small Valve Seat Suction Tool. This can Usually be Purchased for $10.00us and has a Suction Cup that Hold the Valve Head so you can Turn the Valve Back and Forth and Dress up the Valve Seat. Valve Grinding Compound is Approximately $5.00us a Tube and a Tube Last the Shop About a Year. It Doesn't Take a Lot to Reseat 1 Engine.**++**
>> Once the Valve Clearances are Reached and the Valve Seat is Nice and Dull; Re-Install the Valves on that Cylinder and Turn the Other Cylinder to TDC on the Compression Stroke and Set that Cylinders Valve Clearances.
>>Once that Cylinder is Set, then Assemble the Engine.**
>>If After Lapping/Seating the Valves and Setting the Valve Clearance the Engine Still has Low Compression, then the Rings are Worn Out and a Re-Ring of the Engine is Required.
>>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 8pm EST (US). My New Day Starts then. Comments and Ratings are Greatly Appreciated. Thanks.
Respectfully
John
