IGNITION SYSTEM

TM 10-3930-633-34

MALFUNCTION

TEST OR INSPECTION

CORRECTIVE ACTION

ELECTRICAL SYSTEMContinued

1. BATTERY WEAK OR FAILS TO MAINTAIN CHARGEContinued

Step 3. Check alternator belt tension and output.

Tighten alternator belt tension. Replace or repair alternator if output is low and regulator adjustment does not

correct.

Step 4. Check voltage regulator adjustment (see TM 10-3930-633-12).

Adjust regulator to specifications. Replace regulator if adjustment cannot be maintained.

Step 5. Check for excessive use of starter or dragging starter resulting in excessive battery drain.

Tune engine for easy starting or replace a dragging starter.

Step 6. Check for short to ground in electrical wiring.

Correct short condition.

2. STARTER CRANKS ENGINE SLOWLY.

Step 1. Check state of battery charge.

Refer to Item 1, "BATTERY WEAK."

Step 2. Check for loose or corroded battery cable terminals.

Clean and tighten battery cable terminals (see TM 10-3930-633-12).

Step 3. Check for excessive amperage draw within starting motor.

Replace or repair starter (para. 2-6).

3. STARTER WILL NOT CRANK ENGINE.

Step 1. Check for loose, corroded, or broken cables to starting motor and solenoid switch.

Replace defective cables. Clean and tighten all cable terminals (see TM 10-3930-633-12).

Step 2. Check starter solenoid action.

Replace defective solenoid switch.

Step 3. Check make-and-break action of neutral start switch using ohmmeter.

Replace defective switch.

Step 4. Test starter for short or open circuit (see TM 10-3930-633-12).

Replace or repair defective starter.

Step 5. Check starter mounting; if loose, starter pinion may not engage flywheel.

Tighten starter mounting bolts.

IGNITION SYSTEM

1. ENGINE WILL NOT START.

Step 1. Check for spark at plugs; if no spark at plugs, perform all ignition system tests outlined in TM 10-3930-633-12.

Step 2. Examine rotor and distributor cap for cracks, burned areas, corrosion, and carbon tracking.

Replace defective rotor and distributor cap, repair distributor (para. 2-8).

Step 3. Refer to "ENGINE" section of this table for further troubleshooting information.

2. ENGINE RUNS ROUGH OR MISSES.

Step 1. Check all ignition system components as outlined in TM 10-3930-633-12.

Step 2. Refer to "ENGINE" section of this table for further troubleshooting information.

3. ENGINE PINGS OR KNOCKS UNDER LOAD.

Step 1. Check ignition timing.

Adjust to proper timing (see TM 10-3930-633-12).

Step 2. Check distributor advance mechanism for proper operation (see TM 10-3930-633-12).

Repair distributor (para. 2-8).

Step 3. Refer to "ENGINE" section of this table for further troubleshooting information.

ENGINE

1. ENGINE WILL NOT START.

Step 1. Perform checks under "FUEL SYSTEM," (See TM 10-3930-633-12).

Step 2. Perform checks under "IGNITION SYSTEM," (See TM 10-3930-633-12).

Step 3. Check for low compression (para. 6-8).

Overhaul engine (Chapter 6, Section HI).

2. ENGINE BACKFIRES, MISSES OR OPERATES ERRATICALLY.

Step 1. Check malfunctions under "IGNITION SYSTEM."

Step 2. Check for manifold vaccum leak (para. 6-7).

Repair cause of leak, according to test results.

Step 3. Check compression (para. 6-8).

Repair cause of poor compression, according to test results.

Step 4. Check for broken valve spring.

Replace valve spring (para. 6-19).

Step 5. Check for excessive carbon build-up in cylinder head.

Overhaul cylinder head and valves (see Chapter 6, Section IV).

Step 6. Check valve timing.

Align camshaft gear timing marks (see Chapter 6, Section VIII).

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