If you have ever used any tool with a small engine, chances are good that you have had to provide routine maintenance. Even so, you may have trouble getting an engine to start, regardless of how well the engine has been maintained. Knowing how to troubleshoot and identify problems can save you time, and help you get your work done faster. If you are having trouble starting a small engine, use these tips to troubleshoot and fix the problem.
1) Make sure ALL on/off switches are in the on position.
The first step in troubleshooting is to check all the switches to make sure that all the switches are set to “on.” Some units have a kill switch in addition to an on/off switch on the engine. The location of the safety switches may vary based on the brand and unit. Look for the seat switch, brake switch and PTO (power take off) switch to make sure that they are all in the proper position. If you are unsure of how to find the location of a switch, check the manual for your particular unit. It should have a diagram showing the location of each switch.
You can also check the oil sensor to make sure that it shows “full.” If your oil levels are too low, the engine may not start. It may also be prudent to check the stop cable or blade brake. Lawnmower Man gives the following tips for checking the blade brake. “This cable is connected to the handle bar and you have to hold the handle bar down for your engine to run. This cable becomes stretched after some time and needs to be replaced. There is a safety switch on the other end of that cable, on the motor, that will not be opening all the way and in turn, not letting the engine spark.”
2) Make sure the gas is turned on and the tank is full.
Look at the fuel shutoff valve along the gas line, and make sure that it is not turned off. There is typically an indicator on the valve to note the correct “on” position. Take a look at the fuel tank, and see if you can identify any problems. Make sure that there is fuel in the bottom of the tank, and that the ventilation hole at the top of the cap is not clogged.
If the unit has been in storage for several months make sure there is no old fuel left in the tank. If so, you may need to drain the fuel, clean the fuel filter, and fill it with fresh fuel.
3) If the engine is cold, make sure the choke is in the “on” position.
When the engine is cold you need to make sure that your choke is set to closed or “on” position. Physics Forums gives the following explanation for why the choke helps an engine start when it’s cold. “Choke valves are important for normally aspirated gasoline engines because small droplets of gasoline do not evaporate well within a cold engine. By restricting the flow of air into the throat of the carburetor, the choke valve reduces the pressure inside the throat, which causes a proportionally greater amount of fuel to be pushed from the main jet into the combustion chamber during cold-running operation. Once the engine is warm (from combustion), opening the choke valve restores the carburetor to normal operation, supplying fuel and air in the correct stoichiometric ratio for clean, efficient combustion.”
4) Make sure the throttle is at a minimum of 50% of full power.
Most engines won’t start if the throttle is at idle. Many small engines have a governor that helps to control the speed, but some do not. Briggs and Stratton explains the purpose of a governor, stating, “Without a governor, you would need to adjust the throttle manually each time your lawn mower ran across a dense patch of grass. A governor does the job for you by detecting changes in the load and adjusting the throttle to compensate.”
5) If it still won’t start, you could have a blocked air filter, or a clogged fuel filter.
In this case, the engine will require more involved service. If you are unsure of how to proceed, reach out to your nearest Diamond Tool Rental location. Our friendly, knowledgeable staff will direct you in how to proceed so you can get back to the job you rented the tool for right away.
Troubleshoot to Save Time
Even the best maintained engines don’t function properly at times. By troubleshooting a few common problems, you can get to the root of the issue, and be back on track to complete the job. You can save time and money by knowing a few basic tricks to get a small engine running smoothly again.