Small Engines (Lawn Mowers, etc.): 18 HP B&S engine - Hard Starting/Stops Running, gas filter, needle valve

Question
Hi John,
I have an older 18HP B&S Riding Lawn Mower ( Model422707, type 121401, code 9503025B) That had been running ok. I could not get it started so I changed the plugs, regapped magneto -.011, changed gas and gas filter. I pulled flywheel off to replace starter gear and checked flywheel keyway of which was not damaged. I took off front cover of intergal fuel pump on carb and checked diaphragm which was not torn. I checked the compression which is 75 and 85 lbs. The mower will start for a brief moment then shut down. As a sidenote, before the starter gear broke several weeks ago, I did get it started and it ran strong. The next it did not start and that is when the starter gear went. I am very frustrated and would really appreciate your help. Thank you in advance for your help!

Answer
Hello Kevin:

You will have Less Trouble from the Coil and Flywheel with the Coil Gapped at .020in from the Flywheel. Have you Checked the Fuel Shut Off Solenoid in the Carburetor Bowl? Replace the Solenoid with a Bolt About 3/4" Long and Of the Same Diameter and Threads. If the Engine Starts and Runs, then the Solenoid is Bad. **DO NOT OPERATE THE ENGINE WITH THIS BOLT IN PLACE OF THE SOLENOID, PLEASE. REPLACE THE SOLENOID. THIS IS FOR TESTING PURPOSES ONLY. THANKS** Sometimes you can Apply Current and Watch the Plunger Move In and Out to Check the Solenoid Also. If the Solenoid is Good, then is the Gas Pump Primed? Some of these Engine Must have the Fuel Pump Primed in Order for the Pump to Pick Up the Gas and Start to Operate. I Use Compressed Air to Slightly Pressurize the Gas Tank and Push the Gas to the Fuel Pump. The Last Item is the Carburetor Itself. If the Above Components are Operating Properly, then  Remove, Disassemble and Soak 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 Accidential Spillage. Then Blow Out the Passages with Compressed Air. Install New Parts if Required. You can View a Breakdown/IPL of this Engine at this Site Addy, http://www.outdoordistributors.com/ and Select the B. Then Select Briggs and Stratton. Then Select Don't have Part Numbers. Then Select the File # 42. Then Select the Folder # 422700. Hope this Helps. I am Here if You Require More Assistance. Let me Know What Happens, Please. Thanks.

Good Luck

Respectfully

John