Fault location
The following method can be used when the recom-mended oscilloscope (scope) type of test equipment is not available.
1. Remove the coil high tension lead from the distri-butor cap.
2. Hold the high tension lead approximately 3/16 in. from the cylinder head.
3. With the ignition switch on, crank the engine and check for a spark.
If the spark is good, the trouble lies in the secondary circuit from the distributor to the spark plugs.
If there is no spark or a weak spark, the trouble is in the primary circuit, coil to distributor high tension lead, or the coil.
Primary circuit
A breakdown or energy loss in the primary circuit can be caused by:
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1. Defective primary wiring.
2. Burned or Improperly adjusted breaker points.
3. A defective coil.
4. A defective condenser.
Secondary circuit
A breakdown or energy loss in the secondary circuit can be caused by:
1. Fouled or Improperly adjusted spark plugs.
2. Defective high tension wiring.
3. High tension leakage across the coil, distributor cap, or rotor.
Primary circuit tests—See Fig. 98
A complete check of the primary circuit can be made with a voltmeter having a range of 0-2 volts and 0-20 volts. Excessive voltage drop in the primary circuit will reduce the secondary output of the ignition coil, resulting in hard starting and poor performance.
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