Pre Repair No Start Checks
Mower Won't Start
Ignition system Section
Spark test
Armature
Armature provides the voltage to fire the spark plug, armature failure is common.
The video walks you through the process step by step, from checking the armature, checking for wiring short, fitting armature and setting the air gap. This video works for all mowers.
Shear-key
A broken shear-key may cause backfiring, no start and pull cord recoiling sharply.
The video walks you through the process step by step, checking the shear-key, tapping flywheel, removing flywheel, torqueing flywheel. See "Repair Tools" on how to use a torque wrench. This video works for all mowers.
Fuel System Section
Gas shot
Choke test
Gas Bowl Clean
Carburetor Clean
Compression System Section
Compression test
Valve Check
Over View
You’ll find useful resources on this page, tips, links to tools, parts and supplies required to complete your repair.
My mower won’t start is the complaint I most commonly hear in the spring, just after the winter hibernation.
If that sounds familiar, then it’s likely your fuel system is filled with stale gas and so we’ll need to clean it out, it’s a common issue and is covered in these videos.
There are 3 main ingredients an engine must have in order to run (Ignition, Fuel and Compression). One of the 3 is at fault and in these videos we’ll find out.
To diagnose our fault, we’ll run simple tests along the way, the results of each test will guide us towards the root cause of our problem and of course the fix is included.
By the end of these videos you’ll be a pro!
Before working on your mower be sure to remove the plug wire to prevent accidental starting, see “Repair Safety Video”.
Resources
Briggs & Stratton – Most models take from empty .65 US quarts (.6 lts) 5W30 engine oil.
Honda engines – Most take from empty .58 US quarts (.55 lts) of 10W30 engine oil.
Kawasaki engines – Most take from empty .6 US quarts (.6 lts) 10W30 engine oil.
Kohler engines – Most take from empty .6 US quarts (.6 lts) 10W30 engine oil.
For exact specs see:
Tools & Parts
To nail this procedure you may need the following tools, parts and supplies.
Ratchet Tool Set
Before we can do anything, we'll need tools. I've selected this set as I own some Craftsman tools and while I have worn some out, they did do a lot of work. So I expect this set will last the occasional user quite a long time.
This set carries both metric and standard sockets and that's important, because some mowers will have both type of fastener sizes. Set includes spark plug sockets. Picture links to Amazon.com
Gas Line Clamp
DVOM
Compression Tester
This is a compression tester, it's fitted in the plug hole using the adaptor. The engine is cranked over and a reading of how much compression the cylinder makes is captured on the gauge.
A low reading can be caused by a simple fault such as a sticking valve. Picture links to Amazon.com
Impact Wrench
Drill/Screw Gun
Torque Wrench
Teng 1/2 Torque wrench, fantastic tool I use it every day and mine is still going strong. A torque wrench is advised for tightening components such as flywheel nuts and blades. The torque spec of these components is very important. Picture links to Amazon.com
If you are considering buying a torque wrench, definitely check out my review of Teng torque wrench.
Briggs & Stratton
This is a popular Hooai Carburettor fitted to walk behind mowers with Quantum engines, but check the engine codes listed. This is an Auto choke carburettor.
This carburettor has a fuel feed bolt in the base of the bowl, dirt in the bolt feed hole is a common issue. Picture links to Amazon.com
Briggs & Stratton
This is a after market replacement carburettor for the Briggs 4-7hp engines. This is the primer bulb style carburettor.
This carburettor has a fuel feed bolt in the base of the bowl, dirt in the bolt feed hole is a common issue.
It comes with a replacement air filter/primer bulb housing gasket. Without this gasket your primer bulb won't work. Picture links to Amazon.com
Briggs & Stratton
Honda GCV 160
This is a Hooai carburettor fitted to the Honda GCV160 engine only, not the GVC190. It comes with gaskets, plug, filter and fuel line.
Fitting isn't difficult, just a little tedious, take your time and some pictures of where the old gaskets are positioned and their orientation. Picture links to Amazon.com
Honda GCV 190
This is a Hipa GCV 190 carburettor fitted to the Honda GCV190 engine only, not the GVC160. It comes with gaskets, plug, filter and fuel line.
Fitting isn't difficult, just a little tedious, take your time and some pictures of where the old gaskets are positioned and their orientation. Picture links to Amazon.com
John Cunningham is an Automotive Technician and writer on Lawnmowerfixed.com. I've been a mechanic for over twenty years, I use my knowledge and experience to write "How to" articles that help fellow gear-heads with all aspects of mechanical repairs, from lawn mowers to classic cars.