Yamaha F150A - Page 124

4-13
Outboard motor troubleshooting
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A
Spark plug does not pro-
duce a spark
(some cylinders)
Spark plug malfunction
Check the ignition spark. 5-21
Check the spark plugs. 7-25
Short, open, or loose connec-
tion in ignition coil circuit
Measure the spark plug wire resistance. 5-21
Check for wiring harness continuity
between the ignition coil and the engine
ECM.
A-4
Check for wiring harness continuity
between the ignition coil and the main
relay
A-4
Ignition coil malfunction
Measure the ignition coil input voltage. 5-21
Measure the ignition coil output peak
voltage.
5-21
Measure the ignition coil resistance. 5-21
Pulser coil malfunction
Measure the pulser coil output peak volt-
age.
5-22
Measure the pulser coil resistance. 5-22
Fuel pressure is low
High-pressure fuel line mal-
function
Measure the fuel pressure. 6-5
Check the pressure regulator. 6-5
Check the fuel filter for dirt and obstruc-
tions.
6-43
Check the high-pressure fuel pump. 5-18
Fuel not supplied
(some cylinders)
Fuel injector malfunction
Check the fuel injector operation using
the YDIS.
5-17
Measure the fuel injector resistance. 5-17
Measure the fuel injection volume. 6-32
Short, open, or loose connec-
tion in fuel injector circuit
Measure the fuel injector input voltage. 5-17
Check for wiring harness continuity
between the fuel injector and the main
relay.
A-2
Check for wiring harness continuity
between the fuel injector and the engine
ECM.
A-2
Clogged fuel injector filter Replace the fuel injector. 6-30
Engine ECM malfunction Replace the engine ECM. 7-28
Compression pressure
is low
Improper valve timing Check the timing belt. 7-17
Compression leakage
Measure the compression pressure. 7-1
Measure the valve clearance. 7-1
Check the camshaft for damage. 7-35
Check the valve and valve seat for wear.
7-41
7-43
Check the piston and piston ring for
damage.
7-61
Check the cylinder for scratches. 7-64
Symptom 2 Cause Checking steps
See
page