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Small Engines (Lawn Mowers, etc.)/B&S Model 253707 Type 0247-01 Code 86042310


QUESTION: was given 3 Snapper Mowers out of all the motors this one should run. went through the carb cleaned and put back togethere. had  the motor running for a short while but was blowing back out the carb almost like the exhaust valvle was sticking.ran till got warm backfired and hasnt run since.also same thing with a 12hp B&S that was on it the carb needing a rebuild kit(oh have a brand new COIL)and still have weak spark on 12hp.and above model..did these motors require points.if so can i do away with points all togethere some how. need help in trouble shooting these 2 motors really like to use this Snapper Hi-vac (forrest gump age)...Please help (have a realitive good knowledge of small engines but always could learn more).... and can the above model run without governor....

ANSWER: If the code number starts with 81, standing for 1981, then there are no points.  By 86 all Briggs used electronic ignition.

Do you know how to prime an engine?  I use a small bottle with a small hole in the cap for priming.

If the engine starts by priming, then you know the ignition system, compression, valves/timing are in decent shape.  This only leaves the fuel system as the issue.

You should be able to keep the engine running for as long as you want while priming via the carb; you may have to dis-connect or pinch off the fuel line.

If the engine will not run while priming, then you have another issue.  I always start by verifying spark is present and then check the flywheel key as the key controls the ignition timing.

If those are good, and it still won't start by priming, then suspect a valve or compression problem.  Either of these are very easy to detect with a cylinder leakdown test.

Let me know if this helps.

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QUESTION: the 7hp code starts with 70 (170702 0670-61 7006080) engine was running fine till it just shut off and had no spark at all on it (can i do away with the points and not have to use them anymore)

ANSWER: Yes you can do away with the points by either replacing the whole coil with a new style electronic coil or adding an aftermarket electronic ignition module.

You do not have to remove the points wire under the flyweel but it would be better if you did; you can just cut the wire as far back as you can reach under the flywheel.

Will the other coils off the newer engines bolt on the 7 hp?   The 7 hp coil mounting screw holes may be different.


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QUESTION: Thank you for your expertise and yes the bolt holes are exhactly the same...

If the bolt holes are exact, even close enough to bolt on the coil without stressing the screws or mounting bosses then the coils should be interchangeable.

To turn the engine off all you need to do is ground the single, small spade terminal on the ignition module. This is normally done by the key switch on riders but you can use a toggle switch as well.


Small Engines (Lawn Mowers, etc.)

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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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