Pruner: Hard To Start

When your carburetor is functioning correctly, its purpose is to mix air and fuel together at the proper ratio to achieve combustion, which of course, starts your pruner. A clogged or damaged carburetor can make your pruner difficult to start. To assess and/or replace your carburetor, you will first need to locate it underneath the air filter, and remove the air cleaner cap and the air cleaner. At this point you may want to clean out the carburetor. You will need to use carburetor cleaner spray to clean the inside of the carburetor. Next, use a soft bristle brush to gently remove the build up of grime inside the carb. Once you have cleaned the carburetor you will want to check that the choke valve is functioning properly. At this point, the choke should be closed to allow the air fuel mixture to be rich for starting. If it is not functioning properly, it may require a new cable, rod, or switch depending on the model and how it is attached. These cables tend to stretch over time and occasionally they will need to be replaced.

Your pruner’s air can be found on top of the carburetor. Its main function is to allow clean flowing air into the engine and prevent small particles from damaging internal engine parts. Over time the air filter will need to be replaced as it becomes clogged with small particles and debris. A clogged air filter can make cause your pruner to become difficult to start, as it can result in an engine that is starved of fuel. To inspect the air filter, simply remove the air filter cover by the tabs or screws that hold it in place, and if it looks heavily soiled, it will need to be replaced.

The fuel filter is located inside the tank and prevents debris from entering the carburetor and engine, causing damage. You can remove the fuel filter by using a hook and pulling it out of the fuel tank. Check to see if it is partially clogged as this can limit the flow of fuel to the engine. On some models, you may have to remove the grommet on the side of the tank, then push the fuel line into the tank so you can pull the fuel filter up. Next, insert a hook into the tank, pull out the filter and clean out any debris. To replace the fuel filter, pull it gently off the fuel line, replace it with a new one, and re-assemble in reverse order

The gasket’s job is to create a seal that prevents air and fluids from entering the engine. A damaged gasket below a carburetor will pull excess air into the cylinder, and this can make your pruner hard to start. To check for a damaged or loose gasket, start by removing the air filter and loosening the carburetor bolts. With the air filter removed, you can check the condition of gasket. Look for tears or rips or any indications of a leak. Gaskets are a onetime use so you will have to replace it at this point regardless of its condition. Once you have installed a new gasket, you can re-assemble the remaining parts in reverse order.

A properly functioning spark plug will ignite the air/fuel mixture in the combustion chamber. A faulty or damaged spark plug will make your pruner very difficult to start. To check for a damaged plug, remove the wire from plug, taking care not to damage it, as spark plugs can be fragile. Once you have the spark plug removed, you can check its condition. Sometimes on a 2-stroke engine there will be oily build up from improper oil/gas mixture. If this is the case, clean the plug and re-gap to the manufacturer’s specifications. Also, check for any deposits, breakage, melting or corrosion. If you see any of these symptoms replace the plug and gap to the manufacturer’s specifications.

The small bulb that you’re taught to press when starting your pruner, exists to pull fuel through the fuel line into the carburetor by creating a vacuum. Pressing it twice should draw enough fuel into the carburetor to allow it to mix with air for combustion on a cold start up. A damaged primer bulb will make your pruner hard to start, so you will need to check the primer bulb for any leaks. You should be able to tell if your primer bulb is leaking after a quick visual inspection, but the smell of fuel or fuel dripping from the bulb as you press it are indications of a bulb leak as well. To replace the primer bulb, simply pull it off with a pair of pliers. Next grab a small pick and reach into where the bulb came off, grab the clip, and pull it out. Next, you should clean out the housing, and attach the new clip to the primer bulb with the tabs facing out. Then, use a socket that fits over the primer bulb, push it into the housing, and tap it gently with a rubber mallet. Make sure the metal clip is in as far as it can go without damaging the primer bulb. These assembly instructions can vary with different models, but it should be relatively similar regardless of what model you own.

The fuel vent allows air into the fuel tank as the fuel level drops during use. If the vent is blocked, it will cause a vacuum and stop the flow of fuel. This can make your pruner very difficult to start. The fuel vent can be found just off the fuel tank, attached to a fuel line entering the tank through a grommet with the fuel delivery and return lines. To check the fuel vent for blockage, first pull off the clamp holding it onto the line. Keep in mind, you will need a pressure checker to check for a vacuum. Often times, it is easier to just replace the fuel vent, if you don’t have a pressure checker handy.

The purpose of the fuel lines is to deliver fuel from the fuel tank to the carburetor where it is mixed with air for combustion. To clean/inspect the fuel lines, start by pulling the fuel line off the carburetor gently, using a twisting motion, and do the same on the fuel tank. Some models may require you to remove the rubber grommet the fuel line feeds into from the side of the tank first. You can simply blow through the lines, keeping an eye out for anything unusual coming out such as thick oily substances or any other blockages. If you see anything unusual coming out, or discover a partial blockage, it’s best to replace the line. Lines should also be replaced if they look old and cracked, as this can result in a leak as well.