Let's take a closer look into the reasons that prevent a leaf blower from starting, with a little depth.
Gas powered leaf blowers consist of a small internal engine that generally requires only three things to start: air, spark and fuel.
Air must move in and out of the engine in order for it start. This is generally done through an air filter. The foam pads of the filter remove particles such as, dust from the air before it mixes with the fuel. If the filter is dirty, it will prevent air from flowing into the engine, thus preventing the engine from starting. It's recommended that you clean the filter regularly by washing it with soapy water every 10-15 hours and replacing it when the filter becomes to dirty to clean.
The air leaves the engine through the muffler, which lies on the opposite side of the carburetor - (note, some backpack models are different). It vents hot gases from the engine and the operator. The muffler has a metal screen that keeps ignited embers from escaping. If this screen gets clogged carbon builds up and blocks the exhaust. This blockage will prevent the engine from starting. It's recommended that you clean all the ports using a wire brush.
If your spark plug is getting little or no spark, check the plug for signs of wear and damage. A cracked insulator, burned electrode or carbon build up may be a sign of wear on the plug.
Another way to check your plugs is by using a spark plug tester. This checks the spark while the engine is starting. If the spark between the tester terminals is good when the engine is starting, then the plugs are good. However, if there is little or no spark, the plugs need to be changed.
When changing your plugs, check with the manufactures specifications and use a gapping tool to get the correct gap for the plugs. It's recommended that you clean the boot and wire connected to the plug and check the connections. Sparks plugs need to be changed at least once during the season, but if the leaf blower is used frequently then the plugs need to be changed more often.
Sometimes, other spark issues may be the cause for your leaf blowers failure to start. Consult with a professional, as this may be a more complex and expensive repair for your equipment.
In order for any engine to start, fuel needs to be able to flow in and out of the carburetor. This is achieved when the fuel is able to freely cycle from the tank to the carburetor. It's here that the fuel and air mix as they move into the cylinder and the excess gas is purged out via a secondary hose.
However, cycling may not be the issue. Stale fuel can cause an engines failure to start. Stale fuel is the most common issue when it comes to leaf blowers failing to start. Try emptying the tank and replacing the old fuel with fresh gasoline or 2-cycle gas/oil mixture.
If the issues mentioned above doesn't fix your leaf blowers problem, then it may be a compression issue. This is simply when there isn't sufficient enough pressure to keep all the parts moving in sync. Check for leaks around the crankcase and piston. This is often the cause of compression issues. Unless you're a mechanic, you may need to consult with one to help you get your leaf blower in top running order.
As with any engine, proper maintenance is the determining factor between equipment that works and equipment that fails. Even the highest rated leaf blowers need the proper maintenance to function properly.