Engine: Hard To Start

The carburetor creates the proper air/fuel together mixture for combustion. If your carburetor is clogged, it will not be able to provide the proper ratio of fuel and air, and therefore can make your engine difficult to start. To inspect the carburetor, first locate it underneath the air filter and remove the air cleaner cap. You may be able to clean out the carburetor, and replace some of the internal parts that may be clogged or damaged by installing a new carb kit. To clean the carburetor, you will want to use carburetor cleaner and a soft brush for the inside. You should also check that the choke valve is functioning properly. It should be closed to allow for a rich air/fuel mixture 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.

The air filter for your engine can be found on top of the carburetor. Its main function is to filter out debris from entering 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, starving the engine of air. This will result in a loss of power and a hard-to-start situation. To inspect the air filter, simply remove the filter cover by the tabs or screws that hold it in place. If it looks heavily soiled it will need to be replaced.

The fuel filter is located between the fuel tank and the carburetor, and prevents debris from entering the carburetor and the engine, which can cause damage. A clogged fuel filter can starve the engine of fuel, and make the engine hard to start. You can remove the fuel filter by gently twisting the fuel line off both ends and blowing through it. If it is blocked, or you suspect it may be at least partially blocked, then it should be replaced. Inspecting and replacing the fuel should be done as part of your regular engine maintenance routine. When replacing a fuel filter, check for an arrow indicating the direction of fuel flow and be sure to install it the correct way.

The purpose of a gasket is to create a seal between two pieces of metal, and prevent air and fluids from getting into areas where they do not belong. A damaged gasket below the carburetor will pull excess air into the cylinder and make your engine difficult to start. To check for a loose or damaged gasket, start by removing the air filter assembly and loosening the carburetor bolts. Pinch off the fuel line, pull back the carburetor, and remove the linkage if needed. Now you can check the condition of gasket. You are looking for tears, rips, or any indications of leaks. Gaskets are designed for one-time use so you will have to replace it, regardless of condition. You should also clean both mounting surfaces, so that the gasket will seal properly. Finally, slide the carburetor back on, hook the linkage and fuel lines back up, un-pinch the fuel line and re-install the air filter assembly.

The spark plug ignites the air/fuel mixture in the combustion chamber. A damaged or fouled spark plug will make your engine hard to start. To check the spark plug, remove the spark plug wire from the plug; be careful when doing so as the plug can be fragile. Remove the spark plug and check its condition. A spark plug’s normal color should be a light brown or grey. At this point you can clean the plug and re-gap to the manufacturer’s specifications. You will also want to check for any deposits, breakage, melting, and corrosion. If you see any of these symptoms, replace the plug and gap to manufacturer specifications.

The primer bulb allows you to pump fuel into the carburetor, to make it easier for the engine to start up when it’s cold. Usually, you should only need to depress the primer bulb twice to get the desired result. If the primer bulb is cracked, leaking fuel, or if you can hear air entering when pushing it, then the primer bulb is not functioning properly and it will need to be replaced. A cracked primer bulb can also be a fire hazard, as it can result in leaking fuel. To replace the bulb, simply use a small flat-head screwdriver to pry out the old primer bulb, then install a new primer bulb by using a larger flat-head screwdriver to carefully tuck the edges back into place.

Some engines have carburetors that house a diaphragm, which is used to regulate the fuel mixture with air. Over time, this diaphragm will start to deteriorate, and this can cause the rate of fuel to decrease, impacting engine performance. To solve this problem, first remove the air filter housing assembly. Next, remove the carburetor from the engine by unbolting it (make sure you pinch off the fuel lines to prevent a fuel spill). Now you can remove the fuel line. Next, remove the carburetor and the linkages. Disconnect the gasket under the carburetor and remove the screws on the bottom of the carburetor, then pull the bottom off. At this point you can remove the gasket and the diaphragm, and install the new gasket with a new diaphragm. Re-install the cover back onto the carburetor, hook the linkage back up, then reinstall the carburetor back onto the engine with a new gasket underneath it. Now you can re-attach the fuel line to the carburetor (remember to un-pinch the fuel line). Finally, re-attach the air filter housing and filter, and your repair is complete.

A carburetor kit contains everything you need to rebuild your carburetor and restore it to working condition. When rebuilding the carburetor, it’s a good idea to take pictures of all the parts as your taking them apart, so you’re aware of where they go during re-assembly. Start by removing the air filter housing unit and the air filter. Pinch off the fuel line to prevent fuel from flowing everywhere, then remove the fuel line itself. Locate the bolts securing the carburetor to the engine and air intake, and remove them. Next, you will need to disconnect the linkages from the carburetor, and the carburetor should slide right off. Place the carburetor on a bench, and start disassembly by removing the nut on the bowl. Now you can remove the bowl, gasket, float pin, and needle valve. Unscrew the main jet screw and dump it out with the emulsion tube. Then, remove the plastic throttle stop and the metering plug out of the carburetor. Spray the carburetor, fuel bowl, and the small orifices with carburetor cleaner and wipe it clean. If you notice any corrosion inside the carburetor or on the bowl, you will need to replace the carburetor altogether. Once the carb is clean, re-install the new emulsion tube and main jet, and tighten them up. Install a new metering plug, re-install the throttle stop screw and thread it in until it sticks out the other side (about 1/16 of an inch). Next, install the new spring on the needle valve and snap the new needle valve into the new float. Re-attach the float to the carburetor by sliding the new pin in. Install the new bowl O-ring, re-install the bowl, and tighten it down. Once the carburetor is rebuilt, re-install it with a new gasket, sealing it to the intake. Re-attach the linkages and the fuel line and remember to un-pinch the fuel line to allow the fuel to flow. Finally, re-assemble the air filter housing back onto the engine.