AboutJohn C. Bridgers Sr. Expertise Small Engine Service Center Co-Owner - ATVs, Mowers, Trimmers, Snow throwers, and Many Other Small Engine Operated Equipment. I can answer questions pertaining to Most Lawn and Garden Equipment, e.g. riders, tillers, trimmers, cement mixers, chainsaws, etc. I have been repairing small engines for 34 years. Briggs & Stratton, Tecumseh, Kohler, Lawn Boy, Stihl, Poulan, Mac, and Honda; to name a few.
Experience
Past/Present clients I have worked on small air/water cooled engines for 34 Years. I performed warranty work for Lowes of Wilson and other retailers in the area. I Own a Yard Maintenance and Certified Small Engine Repair Service Center.
I have a Troy Bilt TB70SS trimmer with a Zama 1Q carburetor. While trimming it suddenly stopped, as if out of gas, but there was gas in the tank. I suspected the carb was dirty. I tore it down and cleaned all parts. After assembling the trimmer it started fine using the start assist (see attached ZAMA parts diagram part "73". When I pull the throttle trigger which releases the start assist, the engine stops as if not getting gas. The start assist has a plunger that appears to close of extra gas supply. I removed the plunger
assembly and the engine will run, except only at a very high RPM. I'm stumped.
Answer Hello Thom:
Did you Set the Carburetor Mixture Screws? The Statement About "Very High RPM", Tells me the High Mixture Screw is IN too Far and Require Turning Out at Least 1/4 to 1/2 Turn. The Following is the Instruction File for Setting the Air Mixture Screws. Any Input is Appreciated. The Procedure is the Same for 1 or 2 Mixture Screws, Just Use the Instruction File and Skip Over the Section with the Missing Mixture Screw. Now Setting the Air Mixture Screws: ****Turn the Idle Air (L) and Main Air (H) Mixture Screws In Until SNUG **Do Not Jam** Then Reverse Both Screws 1 1/2 to 2 Turns. Holding the Throttle Full Open, Start the Engine. Turn the Main Air (H) 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 (L) Mixture Screw so there is No Hesitation when Throttling from Idle to Full Throttle. Reset the Engine Idle if Required.**** 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.
)