Test 56 - Check Spark Plugs; Test 57- Check Engine / Cylinder Leak Down Test / Compression Test - Guardian 5240 Diagnostic Repair Manual

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Table of Contents

SECTION 4.4

DIAGNOSTIC TESTS

SPARK

TESTER

SPARK

PLUG

LEAD

Figure 26. Checking Ignition Spark

To determine if an engine miss is ignition related,

connect the spark tester in series with the spark plug

wire and the spark plug (Figure 27). Then, crank and

start the engine. A spark miss will be readily apparent.

If spark jumps the spark tester gap regularly but the

engine miss continues, the problem is in the spark

plug or in the fuel system.

NOTE: A sheared flywheel key may change igni-

tion timing but sparking will still occur across the

spark tester gap.

SPARK

TESTER

SPARK

PLUG

LEAD

Figure 27. Checking Engine Miss

RESULTS:

1. If no spark or very weak spark occurs, go to Test 58.

2. If sparking occurs but engine still won't start, go to

Test 56.

3. When checking for engine miss, if sparking occurs at

regular intervals but engine miss continues, go to Test 16.

4. When checking for engine miss, if a spark miss is readily

apparent, go to Test 59.

Page 114

SPARK

TESTER

DISCUSSION:

CLAMP

If the engine will not start and Test 55 indicated good

ignition spark, perhaps the spark plug(s) are fouled or

otherwise damaged. Engine miss may also be caused

by defective spark plug(s).

PROCEDURE:

1. Remove spark plugs and clean with a penknife or use a

wire brush and solvent.

2. Replace any spark plug having burned electrodes or

cracked porcelain.

3. Set gap on new or used spark plugs as follows:

Engine Size

410 cc

530 cc

990 cc

RESULTS:

1. Clean, re-gap or replace spark plugs as necessary.

2. If spark plugs are good, go to Test 62.

SPARK

PLUG

TEST 57- CHECK ENGINE / CYLINDER LEAK

DOWN TEST / COMPRESSION TEST

GENERAL:

Most engine problems may be classified as one or a

combination of the following:

• Will not start.

• Starts hard.

• Lack of power.

• Runs rough.

• Vibration.

• Overheating.

• High oil consumption.

PART 4