Equipment troubleshooting: choose the observed symptom

Work through the model’s fuel and tank-vent checks, then the approved ignition and compression procedures. A brief start does not uniquely identify stale fuel, and starter sound alone cannot establish normal compression.

A very specific fault pattern with a short list of causes: a blocked tank vent, a partly blocked fuel path, a choke that is doing the work, or a coil failing as it warms.

An engine that rises and falls rhythmically is telling you the mixture is wrong. Which way it is wrong, and how the governor turns a small fueling error into a visible oscillation.

The engine is fine and nothing comes out of the sockets. Breakers, the outlet you are testing, and residual magnetism. Worked in the order that costs nothing first.

Stripes, ridges, scalped patches and torn tips are four different faults with four different causes, and only one of them is the blade.

The engine runs, the auger may or may not turn, and nothing leaves the chute. Shear pins, belts, the impeller and wet snow: distinguished by what is and is not moving.

A saw that pulls to one side has uneven cutters or a worn bar; one that smokes and produces dust instead of chips is dull, starved of oil, or both.

Weak or pulsing pressure is usually the water going in rather than the pump, and there is a bucket test that settles it before you take anything apart.

A weak ram, a ram that will not retract, and a visible fluid leak are three separate faults. Fluid level, checked with the ram retracted, resolves more of these than any other single check.

A cultivator can bounce when used on unbroken ground it was not designed to till. Then a slipping drive, wrapped debris on a tine shaft, a bent tine, and depth-stake setting, in that order.

A pack that will not charge, one that drains fast at idle, and one that only weakens under load are three different pack faults, plus the one test that separates a bad pack from a bad tool.

Usually a broken link in the safety interlock chain, the seat switch, the parking brake or neutral position, rather than the PTO clutch itself.

Check whether the pump and suction line have lost prime. Then a suction-side air leak, a clogged intake or impeller, a total head beyond the pump’s curve, and a failed seal, in that order.

Two different faults: not building pressure at all points at the pump or motor; building pressure and then leaking down points at a fitting, a weld, or the check valve.

Every other page tells you when the fault is the carburetor. This one is what to do about it. The case for each of the three options, and the one mistake that turns a cheap carburetor job into a new engine.

A cord that will not pull, one that will not retract, and one that has snapped are three different spring-and-pulley faults, and why yanking harder is how a repairable recoil becomes an unrepairable one.

The one result in the will-not-start sequence that changes the economics. What a real number from a gauge tells you that "the cord pulls easy" does not, and when rings, a valve or a head gasket is worth chasing.

A low-oil shutdown can prevent a four-stroke engine from starting. Check the oil level before replacing ignition parts. A four-stroke that will not turn over at all after being tipped is a different problem entirely, and forcing it is how you bend a rod.

If fresh fuel cannot reach the carburetor, check the valve, filter, lines and tank vent. A cracked line, a primer bulb that will not hold pressure, or a shutoff valve left part-closed, worked in the order that finds each fastest.

Not a symptom to fix: a curve to expect. Roughly how many charge cycles a pack is built for, what capacity fade feels like in use, and the point where a new pack costs less than the runtime you are losing.

A click proves only that the small current that closes the solenoid arrived. A battery that fails under load, a corroded cable end or ground, a failed solenoid contact, then the starter and a locked engine, in that order.

A bang at the air filter and a pop at the muffler are different faults with different causes. Find which end the noise comes from, then work mixture, ignition timing, valves and the exhaust joint.

The engine runs and the mower will not move. The release lever and brake, the drive belt and the linkage come before the transmission, then fluid and trapped air, then the transaxle itself.

A small air-cooled engine has no radiator, so heat means blocked air, thin oil or a lean mixture. An engine that stalls when hot and restarts cool has fuel vapour, a blocked tank vent or a coil that fails as it warms.

The coil is the last suspect, not the first. The plug and its gap, the boot and lead, a stuck kill switch or grounded wire, the coil air gap and the flywheel key all come before it, and each costs little to check.

A machine that stalls or will not start after rain or a long storage. A clear-jar test, draining the bowl and the tank, corrosion in the carburetor, and finding the cap, vent or can that let the water in.