How to Troubleshoot a 2 Cycle Small Engine

Fuel (Carburetor)

• 1

  Place engine on a flat surface. Mounted to the side of the engine is the carburetor. On top of the carburetor is a plastic housing that holds the air filter. Remove air filter cover, it will have a twist off screw that will be hand tight. Clean or replace air filter. Re-install filter and the cover. Turn over the engine, if it does not start move to the next step.

• 2

  Remove air filter cover and filter again, this will expose the carburetor. Spray a small amount of carburetor cleaner in the hole of the carburetor. Turn the engine over, if it starts up and then stalls immediately, replace the carburetor. To replace the carburetor, pull the fuel line from the side of the carburetor.

• 3

  Remove the two flathead bolts that secure the carburetor in place. Twist the carburetor to remove the throttle linkage free. Install new carburetor. Place the throttle linkage back in, bolt carburetor back onto the engine, and push on the fuel line. If the engine did not start, move to the next step.

Electrical and Exhaust

• 4

  Remove and replace the spark plug with the socket and socket wrench. The spark plug is screwed into the engine block and has a black wire connected to it. Turn over engine, if it does not start move to the next step.

• 5

  Unplug the ignition switch and plug in the jumper wire, the jumper wire will bypass the ignition switch. Turn over the engine, if it starts replace the ignition switch. If there is still no spark move to the next step.

• 6

  Install spark tester by clipping to the end of the spark plug and clipping the other end into the spark plug wire. If there is spark move to section 3 (compression). If there is no spark move to the next step.

• 7

  Remove the ignition coil. Remove the four hex nuts holding down the plastic shroud covering the engine. The coil is under the shroud bolted to the engine block is a small black box with the spark plug wire connected to it.

• 8

  Remove the two hex bolts holding the coil in place. Install the new coil. Before tightening down the new coil place the gap gauge in between the flywheel and the new coil to the models specifications listed in the service manual to create a small gap, then tighten down coil. (A business card works as well, it's the exact gap thickness for most coils.)

• 9

  Remove the muffler, there are two hex head screws holding it in place. Flip muffler over and there is a tiny removable screen. If it's clogged, clean and re install. Turn the engine over. If it does not start, move to the final step.

Compression

• 10

  Remove spark plug, and with the flashlight look into the cylinder chamber by shining the light through the spark plug hole. If you see scraping on the side of the cylinder, the engine needs replacement. If there is no scraping move to the next step.

• 11

  Screw in the compression tester by hand.

• 12

  Pull the starting cord several times. Check your service manual for correct PSI range as models differ. A positive or negative range of 20 PSI is in the listed working range. If it reads below 20 or more PSI below the model's working range, the engine needs replacement. In most cases engine replacement cost can exceed the price of the unit being replaced.