Generac Power Systems 5413, 5412 Test 29 - Check Ignition Spark, 32. - Testing Ignition System

Section 7

DIAGNOSTIC TESTS

3.If “Continuity” is not measured in Step 5, repair or replace Wire 0 between the Fuel Solenoid and ground terminal.

4.If “Continuity” is not measured in Step 6, repair or replace Carburetor ground wire.

5.If the Fuel Solenoid operates, proceed to Test 29.

Test 29 – Check Ignition Spark

DISCUSSION:

A problem in the engine ignition system can cause any of the following:

•Engine will not start.

•Engine starts hard, runs rough.

A commercially available spark tester may be used to test the engine ignition system. One can also be pur- chased from Generac Power Systems (P/N 0C5969).

PROCEDURE:

1.Disconnect a high tension lead from a spark plug.

2.Attach the high tension lead to the spark tester terminal.

3.Ground the spark tester clamp by attaching to the cylinder head (see Figure 7-32).

SPARk TESTER CLAMP	SPARk TESTER
GROUNDED TO	SPARk PLUG
CYLINDER HEAD
	BOOT

Figure 7-32. – Testing Ignition System

4.Crank the engine rapidly. Engine must be crank- ing at 350 rpm or more. If spark jumps the tester gap, you may assume the ignition system is work- ing properly. Repeat on remaining cylinder spark plug.

5.To determine if an engine miss is ignition related, connect the spark tester in series with the high tension lead and the spark plug. Then, start the engine. If spark jumps the tester gap at regu- lar Intervals, but the engine miss continues, the problem may be in the spark plug or fuel system. Repeat on remaining cylinder spark plug. Proceed to Test 30.

6.If spark jumps the tester gap intermittently, the problem may be in the Ignition Magneto. Proceed to Test 31.

SPARk TESTER CLAMP
CONNECTED TO	SPARk TESTER
SPARk PLUG
	SPARk PLUG
	BOOT

Figure 7-33. – Checking Engine Miss

RESULTS:

1.If no spark or if engine miss is apparent, go to Test 31.

2.If ignition spark is good, go to Test 30.

Cylinder Balance Test:

If the engine is hard starting, runs rough, misses or lacks power, perform a cylinder balance test to deter- mine whether both cylinders are operating to their full potential.

Tools Required:Two Ignition Testers (Generac P/N 0C5969)

Attach an ignition tester between the spark plug lead and each spark plug (Figure 7-33).

Start and run engine running at top no load speed and note spark at ignition testers. If the spark is equal at both ignition testers, the problem is not ignition related. A spark miss will be readily apparent. Now note RPM of engine. Ground out one cylinder by con- tacting ignition tester and a good ground on engine as shown in Figure 7-34. Note RPM loss. Reattach plug wire then repeat procedure with the other cylinder. Note the RPM loss. If the difference between the two cylinders does not exceed 75 RPM, the amount of work the two cylinders are doing should be consid- ered equal.

If the RPM loss is greater than 75 RPM this indicates that the grounded cylinder with the least RPM loss is the weakest of the two cylinders. Look to that cylinder for a problem.

Example:

Engine RPM - Both Cylinders = 2570 RPM

Engine RPM - No. 1 Cylinder Grounded = 2500 RPM Engine RPM - No. 2 Cylinder Grounded = 2300 RPM

Conclusion: No. 1 cylinder is weakest of the two cylinders.

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