Gas Snowblower: Engine runs rough

A tune-up restores the snowblower to its peak operating condition. A tune-up includes changing the oil, cleaning the engine, replacing the air filter, checking the ignition system, inspecting the carburetor, testing the battery, adjusting the throttle and choke controls, and adjusting and lubricating all moving parts.

Rebuild kits are available for most carburetors. The kit contains the essential components such as jets, pins, seals and gaskets to overhaul the carburetor. You can sometimes fix a fuel supply problem by disassembling and cleaning a carburetor. Use the rebuild kit to rebuild the carburetor after cleaning it.

The snowblower valve lash is the amount of clearance between the top of the valve stem and the rocker arm. Incorrect valve lash prevents the snowblower valve from opening or closing properly. valve lash is incorrect, the snowblower engine is hard to start, runs poorly and loses power. Premature valve failure also results from improper valve lash. Check valve lash after the first 25 hours of use and then every 100 hours. Adjust the valve lash if the snowblower engine won't start or runs poorly.

The snowblower fuel filter screens particles from the gasoline as fuel moves from the fuel tank to the carburetor. Fuel won't flow if the snowblower fuel filter clogs. Replace the fuel filter if it's clogged or damaged.

The snowblower spark plug creates the spark that ignites the fuel, creating a controlled explosion in the cylinder to move the piston that drives the engine. The spark plug won't create spark if deposits build up on the spark plug electrode or if the ceramic insulation cracks. Replace the snowblower spark plug if it's fouled or damaged.

Over time, varnish from stale gasoline builds up in the carburetor, decreasing the amount of air/fuel mixture reaching the engine. Replace the carburetor if it's severely clogged with varnish or if the orifices are clogged with debris and can't be cleared using carburetor cleaner and compressed air.

The sump at the bottom of the engine houses the oil pump and collects engine lubricant. A leak in the sump gasket decreases engine compression, making it difficult to start the engine. If physical examination of the sump gasket reveals a leak, replaced the gasket.