RNLI Atlantic 85, Руководство пользователя

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Activity 9 - Propulsion and Auxiliary Systems
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B Class Atlantic 85 Manual – First Issue, June 2017
Activity 9 - Propulsion and Auxiliary Systems
Spark plug testing
When fuel is present but an engine fails to start or mis-fires,
the spark plugs should be considered a suspect. Remove
the plugs and visually check for fouling or damage.
When testing for a spark, to prevent damage to the
electronics, always use the RNLI supplied spark-tester.
Connect the four leads to the suppressor caps and turn
over the engine. Each lead should produce a fat blue spark.
Ignition control
The ignition timing is mainly determined by signals from
the throttle position sensor and the pulser coils.
Corrections are controlled by the water temperature
sensor, the oil pressure switch, the shift position switch,
the engine stop switch after engine start and the main
switch.
During cranking, the timing is at 10 degrees Before Top
Dead Centre (BTDC) until the engine starts, then it is
retarded 1 degree per second until it reaches 4 degrees
After Top Dead Centre (ATDC). It stays at this point until
the engine is warm.
The timing is usually controlled between 4 degrees
ATDC and 26 degrees BTDC. At rapid acceleration, or
deceleration, ignition timing changes according to the
throttle valve-opening angle.
Pulser coil
The two pulser coils are also located under the flywheel.
They provide a signal to the ECU telling it when to supply
the 12V charge to the two ignition coils.
Ignition coil
The two ignition coils supply the four spark plugs with a
high-tension secondary voltage of between 15,000 and
40,000 volts. One coil supplies plug numbers 1 and 4, and
the other numbers 2 and 3.
Spark plugs:
A spark plug uses the high tension current generated by
the coils to produce a spark of such intensity that it ignites
the compressed fuel and air mixture in the cylinder head.
It is essential that the correct spark plug is fitted, in this
case an NGK LFR6A-11. The electrode on the plug should
have a gap of between 1.0 and 1.1mm. This gap can be
checked with a wire gap tester (K-1392).
Spark plugs can fail quite quickly and should be one of
the first items investigated should an engine give trouble.
When replacing a spark plug care must be taken to ensure
the threads are not ‘crossed’ and that the plug is not over
tightened as this may cause material failure later.
If a torque wrench is available the plugs should be
tightened to a torque setting of 25 N m or 18 ft lbf.