Specifications

Ignition

Troubleshooting the Ignition System

The purpose of the ignition system is to provide a spark in the combustion chamber at the proper time to ignite

the fuel/air mixture.

To troubleshoot the ignition system:

1. Examine the spark plug by following the steps

described in the spark plug section of this chapter.

2. After examining the spark plug, reinstall it, or a new

one to ensure a good spark plug is being used.

3. Disconnect the spark plug wire.

4. Connect a spark tester to the spark plug wire.

5. Connect the other end of the spark tester to the

engine block. See Figure 4.1.

NOTE: It only takes 1,000 volts to jump a 0.025” air gap in open atmosphere, it takes 10,000 volts to jump the

same gap at 120 psi, therefore an open air spark test in not valid.

NOTE: The spark should be a minimum of 10 Kv (10,000 volts) at pull over speed.

6. Make sure the engine stop switch is in the “RUN”

position.

NOTE: Since 2005, most stop switches used on MTD

handheld products are spring loaded to the “RUN”

position when they are released. This prevents no-

start situations caused by the customer failing to

turn the switch on.

NOTE: Once the engine stop switch is moved to the “OFF”

position, it sends a ground signal to the module.

The circuitry in the ignition module will latch the pri-

mary winding to ground until the engine stops. This

prevents the need to hold the switch in the “OFF”

position until the engine comes to a complete stop.

7. Rapidly rotate the engine while watching the spark

tester for sparks. See Figure 4.2.

8. If no sparks are seen in the spark tester, test the

module.

Figure 4.1

Spark tester

Never remove the spark plug and hold it against the engine block to test for spark. The fuel/

air mix coming out of the spark plug hole will catch on fire.

! CAUTION! CAUTION

Figure 4.2

Spark

CHAPTER 4: IGNITION

For Parts Call 606-678-9623 or 606-561-4983