GENERAL INFORMATION
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that are difficult to diagnose. If the engine
occasionally misfires or cuts out, use a spray bottle
to wet the direct ignition coil or plug cap and plug
cable while the engine is running. Water that enters
one of theses areas causes an arc through the
insulating material, causing an engine misfire.
NOTE
Engine misfire can also be caused by water that
enters through connectors. Check the connectors
for loose wire ends. On waterproof connectors,
check for damage where the wires enter the
connector.
6. Perform the Spark Test in this section. If there is a strong spark, perform Step 7. If there is no spark
or if the spark is very weak, refer to Ignition System Testing in Chapter Ten.
7. If the fuel and ignition systems are working correctly, perform a leak down test (this chapter) and
cylinder compression test. If the leak down test indicates a problem, or the compression under
Engine in this chapter.
Spark Test
Perform a spark test to determine if the ignition system is producing adequate spark. This test
should be performed with a spark tester. A spark tester looks like a spark plug with an adjustable gap
between the center electrode and grounded base. Because the voltage required to jump the spark
tester gap is sufficiently larger than that of a normally gapped spark plug, the test results are more
accurate than with a spark plug. Do not assume that because a spark jumped across a spark plug gap,
the ignition system is working correctly.
Perform this test on the engine when it is both cold and hot, if possible. If the test results are positive
for each test, the ignition system is working correctly.
CAUTION
After removing the direct ignition coil or spark plug
cap and before removing the spark plug in Step 1,
clean the area around the spark plug with
compressed air. Dirt that falls into the cylinder
causes rapid engine wear.
1. Disconnect the direct ignition coil or spark plug cap. Check for the presence of water.
2. Visually inspect the spark plug for damage.
3. Connect a spark tester to the direct ignition coil or spark plug cap. Ground the spark tester base (or
spark plug) to a good ground. Position the spark tester or spark plug firing tip away from the open
spark plug hole. Position the spark tester so the electrodes are visible.
WARNING
Mount the spark tester or spark plug away from the
spark plug hole in the cylinder. If the engine is
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