Small Engines (Lawn Mowers, etc.): Ryobi string line trimmer will not stay running, carburetor jets, carburetor body


Question
Hello: The numbers on this trimmer are as follows: Engine family SN 4031wb 24RA EM 1366 1995 California emmissions. I got this machine from a neighbor of mine who gave up trying to get this machine to run several years ago. It will run as long as you press the primer bulb slightly as it runs. It will also run wide open nicely until it runs out of fuel if you stop pressing the bulb in about 10 seconds. I have done the following to it: changed all fuel lines, primer bulb, the internal parts to the carb, blew air thru all passage ways in carb, checked the muffler for and engine exhasust port for exessive carbon and there was none. The 2 clinder bolts are tight. Spark plug gap is.020. There is one thing that I do not understand is: There is a small hole in carb mounting flange that lines up with a hole in the base of the carb, but the hole in the carb is a blind hole that goes nowhere. I also do not see any way for the fuel pump to get a pulse from the engine in order to work. I do not know if anyone has change the carb which is a WT 340 Walbro. The engine is a 31 cc engine. I have put air thru the fuel lines back to the tank and it will pressuerize. I have run it with the fuel cap off also and it still dies after running out of prime. Any ideas would greatly be appreciated. Thanks  JERE

Answer
Hello Jere:

Did you Soak the Carburetor in Carburetor Cleaning Solution? If Not, then the Carburetor Jets can Still be Restricted.  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 Accidential Spillage. Then Blow Out the Passages with Compressed Air. Install New Parts if Required. Have you Checked the Exhaust Port and Muffler for Blockage? You can View a Breakdown/IPL of the Carburetor at this Site Addy, http://69.16.165.8/ and Select Service & Aftermarket. Now Select Aftermarket Parts and Service. Now Select the OEM (Ryobi). Now Select Trimmer. Now Select your Carburetor (WT-340) from the List Provided. Is the Air Mixture Screws Set Correctly? 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 the Farthest from 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 **Don 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.****  Hope this Helps. I am Here if You Require More Assistance. Let me Know What Happens, Please. Thanks.

Good Luck

Respectfully

John

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Respectfully

John