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Small Engines (Lawn Mowers, etc.)/Craftsman 7hp Briggs engine backfires, mis firing.


Hi again. I'm working on a Craftsman push mower with a 7 hp Briggs engine model number 128T02 1270 B1 . Its the model with the auto-choke feature and suppose to start on first pull. When I first got it, it wouldn't start without cranking 10-15 times, and missed when it did finally start. I thought it acted like carburetor problems, so I took it off and rebuilt it, cleaned fuel tank and reassembled. Then when trying to start it, it did start after cranking about four times, but still had the miss in it. I noticed it also had oil looking place on the bottom corner of engine below the head, in between the head and block. I thought it may have a blown head gasket and replaced it. Now it starts on first or second pull, but still missing. I have put a new spark plug in it and air filter. Is the problem still with the fuel system? I have removed and disassembled the carburetor again and now have it soaking in a can of carb cleaner. Am I on the right track or is it something else? Thank you, Sam

Make sure the engine shut-off cable, aka compliance cable, it fully pulling the brake/shut-off switch to the open position.

I have the same engine on my Snapper and it was missing.  Tried the same things you have, cleaned carb, replaced plug.  Turned out the cable was not fully pulling the shut-off switch open.


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Eric A. Jones


Lawnmower Repair . Certified Master Service Technician from B&S. Have 23 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.


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. Continued working on mowers part time as I completed 20 years of military. Retired from the military on a Friday and continued in the lawn and garden industry the next Monday.

MAS Aerospace Operations BA Mathematics AAS Electronic Communications AAS Electronic Technology

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