Starting Small Engines - Equipment & Machines

Why Does My Small Engine Not Start???

1. Was the seasonal maintenance done?

Seasonal maintenance includes cleaning / replacing the air filter, spark plugs, fuel, oil and mechanical linkages and bearings and stabilizing or emptying the fuel out for the storage months. If this wasn't done, start at the Season Prep page on the right.!

2. Is the run / stop switch on?

The stop button is a switch that shuts off or shorts out the electricity to the spark plug. Sometimes the switch is on the throttle control, sometimes as a separate red switch somewhere on the unit.

3. Check fuel tank for the proper type of fuel.

It requires the proper type of fuel for the engine to start. There are different fuels for different engines. Look on the gas cap; If there is an oil drop it means it requires a gas / oil mixture (two stroke engine). A 4 stroke engine requires regular gas and will smoke or be hard to start / idle with oil in the gas. Diesel in the gas tank will not work and requires complete examination by a professional repair service, and gas in a diesel tank will cause an explosion.

4. Check fuel tank for fuel level.

There may be low fuel or too little fuel for engine to start. You really want to start a job with a full tank of fuel anyway.

5. Check fuel cut-off valve

Usually located near or on the bottom of the fuel tank. Make sure it is ON. The tab or handle should point in the direction of the fuel flow, not 90 degrees from it.

6. Does carburetor have a primer bulb?

If so, press it three to five times before attempting to start engine. This will fill the carburetor with fresher fuel.

7. Are you using fresh/clean fuel?

Use fuel less than 90 days old unless fuel stabilizer has been added.

8. If the engine is cold, have you choked the engine?

Or have you choked it too much and flooded the engine?

9. Are all safety switches closed?

Check the seat, blade, reverse and other safety switches.

10. Check spark plug for wetness (fuel) after cranking.

Is the plug dry? If it is then;

• Check the fuel filter. On some engines it is inside of the fuel line at the gas tank, sometimes it is inside the fuel tank or as a separate bulb in the fuel line.
• Check the fuel line and replace if there is any restriction, crack, leak or if it is plugged.

Is plug wet? Make sure the carburetor is not leaking fuel directly into the engine. If it is then;

• Shut off the flow of fuel using either the fuel cut off valve OR pinch or remove the fuel line and plug it off.
• Remove the float bowl bolt on the bottom of the carburetor OR remove the carburetor from the engine to open it on the bench if necessary.
• Gently remove the pin holding the float and remove the float and the needle valve.
• Use small tubing to gently blow through the needle valve seat in the reverse direction of normal fuel flow to make sure that there is no blockage in the fuel inlet.

11. Check spark plug for proper spark.

Spark should be blue, not yellow. There are spark testers available, but it can be tested with the spark plug out and resting on the engine while engaging the starter.

12. No spark problems could be bad coil or stator.

If you suspect either of these take to shop and have checked. It needs special tools and techniques for each type of engine.

13. Try new spark plug

If the plug in use is old, dirty or cracked.

14. Perform a compression test

It is time to visit the small engine repair shop near you! They have the tools, parts and books / specifications required for deeper diagnosis and repair.