STIHL MS 250 Chainsaw Hard To Start When Hot

Ignition Module

The ignition coil's internal primary or secondary windings often develop microscopic fractures that expand when the engine is hot, causing an electrical open-circuit or weak spark condition. Once the saw is shut off, heat soak from the cylinder head intensifies this expansion, preventing the coil from generating the 15,000+ volts required to bridge the spark plug gap during a pull-start until the unit cools down.

SKU: 1123 400 1301

Carburetor Rebuild Kit

Aging rubber diaphragms in the carburetor lose their stoichiometric resilience over time; when the engine is hot, these components can become overly soft or 'tacky,' leading to a failure to properly pump or meter fuel during the low-vacuum conditions of a manual pull-start. This often results in a vapor lock or a flooded condition where the needle valve fails to seat correctly due to thermal expansion.

SKU: 1123 007 1061

Spark Plug (NGK BPMR7A)

Thermal stress can cause the internal ceramic insulator or the resistor element of the spark plug to develop high resistance when hot. This impedes current flow at the exact moment the engine's higher internal combustion chamber temperatures require a stronger spark to achieve ignition, making the saw significantly harder to fire compared to a cold-start state.

SKU: 1110 400 7005