Test Sequence - Mercury 45 Jet 50-55 Service Manual

Test Sequence

1-A) Check primary input voltage to coils (See Test
Chart)
1. If voltage readings to coil(s) are BELOW specification,
proceed with Step 2-A.
2. If voltage readings to coil(s) are WITHIN specifica-
tions, proceed with Step 1-B.
1-B) Check coils for spark. [Connect Spark Gap Tester
(91–63998A1) between coil high voltage tower and
spark plug.]
1. No spark or weak spark. COIL is bad.
2. Spark is OK, proceed with Step 1-C.
1-C) If Step 1-A and 1-B check OK, replace spark plugs.
If problem exists after replacing spark plugs, proceed with
Step 1-D.
1-D) If Steps 1-A, 1-B, and 1-C check OK, check igni-
tion timing.
1. If ignition timing does not check to specification (or a
sudden or unexplained timing change occurs) check
trigger advance linkage for loose and/or broken parts
and check trigger magnet ring (on flywheel hub) for
looseness and/or a shift in position.
2. If ignition checks to specification and engine does not
run or runs poorly, trouble exists with fuel system or
engine mechanical.
2-A) Check switch box "stop" circuit. (See Test Chart).
1. If reading is BELOW specifications, proceed with Step
2-B.
2. If reading is ABOVE specifications, the Trigger or
Switch Box is bad (test trigger as outlined in this ser-
vice manual section; if trigger checks OK, replace
switch box and repeat check).
3. If reading is WITHIN specifications, proceed with Step
3-A.
2A-2 - ELECTRICAL and IGNITION
2-B) Check ignition switch/wiring, as follows:
CAUTION
!
To prevent engine from starting, remove spark plug
leads from ALL spark plugs and ground leads to en-
gine.
1. Disconnect ignition switch and stop switch leads
from switch box and isolate the leads.
2. Repeat check in Step 2-A.
a. If reading is still BELOW specification, proceed
with Step 3-A.
b. If reading is WITHIN specification, either the igni-
tion switch, stop switch, or wiring is bad.
3-A) Check stator low speed and high speed input to
switch box. (see Test Chart).
1. If either the low speed or high speed reading to switch
box is BELOW specification, Stator or Switch Box is
bad (test stator as outlined in this service manual sec-
tion; if stator checks to specification replace switch box
and repeat check).
2. If both the low speed and high speed reading are
WITHIN specification, replace switch box and repeat
test.
90-817643R1 DECEMBER 1996