Small Engines (Lawn Mowers, etc.): B&S 18.5 Horse power OHV Engine Wont Start ?, adjustable gap, ohv engine


Question
Howdy,
I have the following Mower:
Murray Select Mower 425600X8A
Engine # 31D777, Type 0235E103, Code 311ZE

I've done the following:
New fuel filter, fresh gas, new sparkplug, fully charged battery, new air filter, changed the oil.

1.  It will turn over but will not run.
2.  Pulled the sparkplug, it had a little gas on it.
3.  Peformed a spark test, via spark tester with adjustable gap setting.  Had good spark over the gap setting per the recommended setting in the manual .030".
4. Compression Test:  130 PSI.   Is this good?
5. Removed the carburator, and took out the main jet, nozzle, and needle and seat.
Sprayed Carburator Cleaner in all the passage ways.
Everything appears to be clean.
6. Reassembled the carburator and installed new needle and seat.
7. Afterfire solenoid is working:  
When the solenoid is energized, the plunger is retracted
Denergized, the plunger is extended.
8. Removed the flywheel, to check for a sheared key.
It was fine!  Reassembled.
9. Installed a 2nd new sparkplug.
10. Turned it over again but never would crank!
11. Sprayed carburator cleaner into the carburator, The engine ran briefly until the carburator cleaner that reached the combustion chamber was used up.

My conclusions:

a) Getting Good spark,
b) Engine turns over
c) Getting gas to the fuel bowl
   I dont think any is getting to the combustion chamber?
d) Good Compression

Any where else to look?  Do I have a bad carburator?

Thanks for all your help,

Chuck  

Answer
Hello Chuck:

Sorry for the Delay. This Question was Located in the Question Pool and I can Only Answer Questions from the Question Pool when I am Not Answering Questions here or at the Other Site I Answer Questions at. Also, I am on Vacation and had a Few Minutes to Answer a Few Questions. From your Description it Sounds like the Carburetor Solenoid (Afterfire/Anti-Diesel Solenoid) May Not be Moving Far Enough to Allow Gas through the Jet or the Carburetor Requires a Good Soaking and Cleaning. I Suggest you; 1- Check the Carburetor Solenoid (Anti-Diesel Solenoid) as Described in the Instruction File that Follows. The Following is a Basic Instruction File I made for Checking the Carburetor Solenoid. Any Input is Appreciated. **Check for Current/Voltage (10.5 VDC Minimum) to the Carburetor Shut Off Solenoid. If the Carburetor Shut Off Solenoid has Current, then On Some Solenoids you can Remove the Needle and Replace the Solenoid to Test them. ****PLEASE DO NOT OPERATE THE MOWER WITH THE SOLENOID BYPASSED IN THIS MANNER. THIS IS "ONLY" FOR TESTING.**** For Others, Remove the Carburetor Solenoid and Go to the Hardware Store. Purchase a Bolt of the Same Diameter and Threads.It Needs to be 1/2" to 3/4" Long for the Horizontal Mount Solenoids and 1/4" Long for the Vertical Mount Solenoids. Put this Bolt in Place of the Solenoid. If this Corrects the Engine Problem, then Replace the Solenoid. ***NOTE: THIS IS FOR CHECKING THE SOLENOID ONLY I NEVER SUGGEST YOU OPERATE THE ENGINE WITH THE SOLENOID OUT OF THE CARBURETOR EXCEPT FOR TESTING PURPOSES*** Sometimes the Plunger is Moving, Just Not Far Enough to Allow the Gas to Enter the Jet.**  2- If the Carburetor Solenoid ( Afterfire/Anti-Diesel Solenoid) Checks Good, then Soak and Clean the Carburetor; The Cost of the Cleaning Solution I Use is $30.00us @ Gallon (I Use Gunk). The Gallon Can Comes with a Tray for Small Parts and the Carburetor Fits Nicely. Most Times a Carburetor can be Soaked and Cleaned and with the Float, Needle Valve and Other Carburetor Components being Soaked in the Cleaner with the Carburetor Body; there are No Parts to Replace on this Carburetor. If you Soak and Clean this Carburetor and the Float Needle Valve Still Does Not Stop the Gas Flow Properly, then Purchase a Needle and Seat Kit and Replace it. The Following is a Basic File I Made for Cleaning Carburetors. Any Input is Appreciated. The Most Common Cause is; The Carburetors Internal Passages are Restricted by Varnish that Gas Forms Over Time. This Varnish is in Layers. To Properly Remove this Varnish you have to Soak the Carburetor. The Following is a General Instruction File for Carburetor Cleaning. Even though the Carburetor Looks Clean, the Internal Passages May be Restricted with Varnish that Gas Causes to Build Up over Time. I Suggest you Make Sure the Gas is Free Flowing to the Carburetor Inlet Port (if the Model does Not have a Fuel Pump). If the Gas is Free Flowing to the Inlet Port, 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 (if Applicable), Float Pin (if Applicable), Float (if Applicable), Needle Valve and Needle Valve Seat if Applicable. This is a Flat O-Ring Located in the Inlet Port the Float Needle Rests in. Use a Strong Wire with a Slight Bend to Remove the Old Seat. Sometimes a Small Pocket Screw Driver can be Use Also. The New Seat will have a Slightly Beveled Side and a Flat Side. The Flat Side goes Towards the Carburetor Body when Inserted into the Inlet Port. Spray the Seat with Spray Lubricant to make Installation Easier. The End of a Drill Bit that is Slightly Small than the Seat can be Use as an Insertion Tool. Wear Gloves or Use a Rag when Handling the Sharpened End of the Drill Bit. Remove 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.*** (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. 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. 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. 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. You can View a Breakdown of this Mower At this Site Addy; http://www.smallenginepartswarehouse.com/parts.asp and Select Shop Online Parts Lookup. Select the Model Tab. Select the OEM and Enter the Model Numbers. Now Double Click on your Model in the Results Area. Now Select Sectional View. Now Select the Section of the Mower you Wish to View.  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. 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. Thanks.

Respectfully

John