·9 DIY Briggs & Stratton lawn mower not starting - no spark.
Briggs & Stratton lawnmower type small engine Won't Start or Run — No Spark Problem — Check - Fix - Repair
Briggs & Stratton small engines can be found powering many pedestrian-operated walk-behind vehicles and portable machines; your lawnmower most likely uses one of their engines. Other popular applications include; portable generators, pumps, soil tillers, and cement mixers, all of which may have a small petrol / gasoline engine to drive the machine, made by Briggs & Stratton. Of course, Briggs & Stratton are not the only folk making small engines, other manufacturers include Honda, and Kawasaki, for example.
Every spring and summer for the last 25 years I've used my little lawnmower powered by a Briggs & Stratton engine — it never misses a beat and always starts first time - and with that reliability benefit in mind, I really do wish I'd purchased a Briggs & Stratton-engined chainsaw! Am I a Briggs & Stratton fan? Yes Sir, I am!
But today, my focus is on my (normally!) super-easy-to-start 10+ year-old Briggs & Stratton 4-stroke petrol-powered portable generator which generates "household" AC current because that's the machine that I need fixing without delay. I need that portable generator up and running to use power tools in places where extension cables are not practical. For example, I put the genny in the trailer of my tractor and I can use lights and electrical power tools that I need to fix or build something elsewhere. It's well handy, hence the name, "Handy Gen 2500a". The label on the top says it's powered by a Briggs & Stratton Quantum LSQ 55 Silent System.
But what do I do if it won't start or start easily?
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| my Handy Gen 2500 |
My troubleshooting guide checklist for a small engine no spark scenario such as a, "it's turning over, but not starting" issue:
- The on/off ignition / engine cut-off switch is ON to enable starting (not off, or stuck mid-way between on-and-off),
- The on/off ignition switch / engine cut-off is not faulty internally. There should be NO continuity (no circuit) between the switch's two terminals if the ignition switch is on the ON position. If you have more than two terminals on your switch you'll have to find out their purpose in order to test it,
- The ignition "kill-switch" or "cut-out" cable from that ignition switch to the armature / ignition coil is not bare anywhere along its length and touching the engine or chassis, or that the cable's spade connectors are not touching the engine or chassis,
- That the spark plug is proven good or swapped out for a brand-new spark plug and is the correct type for the engine and gapped correctly,
How To Test / Check a Spark Plug — watch a short 51 second video by @HowToBloke - That the high-tension lead from the ignition coil to the spark-plug is not split, disintegrating or damaged,
- The spark-plug top or cap makes good contact with the spark-plug lead socket inside the spark plug cap boot, if fitted.
- That the general area is dry and not dripping in moisture or soaking wet.
- Armature / ignition coil is at the correct distance from the flywheel / rotor magnet measured in thousands of an inch or fractions of a millimeter.
- Armature / ignition coil body does not appear damaged or abnormally bulging in any way,
- Armature / ignition coil has the correct side facing uppermost,
- Armature / ignition coil has internal electrical resistance values that are within the prescribed tolerances / range measured in ohms (that being said, I found it's just a rough guide).
You can see in the above photo that my old armature / ignition coil (part number 802574) is marked CYL SIDE meaning cylinder side, so any new replacement ignition coil must be fitted the right way up.
Finding the correct ignition coil and other engine parts for your particular Briggs & Stratton engine; an Engine number guide:
- Model = 12X812
- Engine = 0119 B1
- Code = 04050356
To find this information on your Briggs & Stratton small engine, use their on-line website guide here Locate Your Model Number
To find a supplier for the spare part that you need, all you do is search on-line using the Model Number and the Engine Number like this for example 12X812 0119 B1 and you should find web sites on-line selling the bits you need.
On many of those web sites you'll discover an exploded-view parts diagram shown interactively or as a .pdf where you can visually search for the part and get its official Briggs & Stratton part number. With a Briggs & Stratton part number it is possible to search for a genuine OEM (original equipment manufacturer) part or replacement spare part.
To find out more about choosing and gapping the correct spark plugs for your Briggs & Stratton small engine, here is their on-line page about spark plugs and spark plug gaps.
https://www.briggsandstratton.com/eu/en_gb/support/faqs/browse/identifying-the-correct-spark-plug-and-gap.html
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| Spark Plug 4106J |
I'm no expert on fixing engines. All what I've learned is self-taught through necessity and experimentation since my teenage years using old cars and motorbikes as my daily drivers. So, please don't rate my DIY repairs as a definitive example of how it should all be done - it is not a professional tutorial !
My son is working with me in the video to fix the motor and I teach and involve him in just about everything I do and pass-on know-how about many, many things which hopefully he'll put to good use after I've popped my clogs. It will help him save some money, and should help him avoid any needless stress and anxiety whilst navigating life's many twists, turns, and cul-de-sacs!
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SAFETY NOTICE: If you choose to work on any engine, always remember, Safety First!
