AboutEric A. Jones Expertise Lawnmower Repair . Certified Master Service Technician from B&S. Have 13 years experience on B&S, Lawn Chief, Weed Eater, Echo, Peerless, Wheel Horse, Snapper, Atlas, MTD, McCulloch, Homelite and many other numerous brands. Specialize in electrical repair.
Experience Born and raised in the midwest. Started tinkering with engines when I was about 14 on my Suzuki RM-80. I began lawn mower repair at a small hardware store. I knew absolutely nothing. I read lots of repair manuals and met an older fellow who taught me many lessons. I continued working on small engines through high school and paid my way through college working on mowers at the same hardware store. Decided to get away from the midwest and mower repair so I joined the Air Force. I repaired air traffic control electronic equipment and ended up in Hawaii where I got a part time job at Small Engine Clinic. I gained a lot of experience from the Small Engine Clinic and had a blast repairing small engines. I then took the Briggs and Stratton Master Service Technician test and earned my MST. I then traveled to Wisconsin where I attended the factory update training seminar and received formal training. I received a scholarship from the Air Force and am currently pursuing another degree.
Question Hi. I read your recent response concerning this same question. I am helping an older gentleman with his JD 400. The enine surges typically at WOT until it warms up then eventually smooths out. I have replaced points, condenser, plugs, hi tension leads and set timing to no avial. We then removed carb and rebuilt and also replaced throttle shaft. Same symptoms occur, surges until warm up. I then removed gov. linkage to carb, and moved carb throttle manually. No surging at all, but I did notice gov. linkage kicking back and forth while I held the throttle at a steady speed. With gov linkage disconnected and me moving throttle shaft, engine runs very smooth. For tune up specs. we used the JD service manual applicable to this engine. The JD manual in trouble shooting suggests surging could be to a faulty govenor,along with other trouble shooting suggestions which we accomplished. Thank you very much and looking forward to you response. Mark D.
Answer Have you replaced the governor spring and checked the engine RPM. The internal part of the governor rarely fails...if it does the engine will run very, very fast and you will have no throttle control.
Normally on these older engines I'd recommend checking the throttle shaft but you've replaced it. Was the old one pretty wore? I usually find them in bad shape.
Back the governor spring. An old spring will sometimes loose tension; this it rare but it can happen. Also, some engines are more sensitive to governor spring tension...the more sensitive it is is usually better except if it constantly surges.
Also, check the engine mounting bolts. Loose bolts cause more vibration which could be vibrating the governor spring. One book I read said you could take a pencil eraser, the kind on a wooden pencil, hold the eraser end on the spring to see if it smooths out the engine. This supposedly checks for vibration and weak springs. Don't know for sure if it works but you might give it a try.
Does the manual tell you the engine RPM?
Let me know.
Eric
