Yamaha F30B 2018, Service Manual

Page: 72 / 348

4-9
Outboard motor troubleshooting
S ymptom 1: Unstable engine idle speed, poor acceleration, poor performance, or limited en-
gine speed.
—
Intake air passage malfunc-
tion
Check the ISC valve for sticking. 5-20
Check the intake manifold and throt-
tle body for air leakage.
6-12
Symptom 2 Cause Checking steps
See
page
Throttle valve does
not move properly
Throttle valve malfunction
Check the throttle valve for proper
movement.
6-13
Throttle link rod and the
throttle cable are not in-
stalled properly
Adjust the throttle link rod and the
throttle cable. 3-6
6-15
Spark plug does not
produce a spark
(some cylinders)
Spark plug malfunction Check the spark plugs. 7-40
Short, open, or loose con-
nection in ignition coil circuit Check for wiring continuity between
the ignition coil and the engine ECM.
A-15
Ignition coil malfunction Measure the ignition coil resistance. 5-29
Spark plug cap malfunction
Measure the spark plug cap resis-
tance.
5-30
Engine ECM malfunction
Check the engine ECM output peak
voltage.
5-29
Fuel pressure is low
Fuel leakage Check for fuel leakage. 2-15
Clogged fuel filter element
Check the fuel filter element for dirt
and obstructions.
6-5
Clogged fuel strainer
Check the fuel strainer for dirt and
obstructions.
6-22
High-pressure fuel line mal-
function
Check the high-pressure fuel pump. 5-24
Pressure regulator mal-
function
Check the pressure regulator. 10-7
Fuel not supplied
(some cylinders)
Fuel injector malfunction
Check the fuel injector operation us-
ing the YDIS.
5-23
Measure the fuel injector resistance. 5-23
Short, open, or loose con-
nection in fuel injector cir-
cuit
Measure the fuel injector input volt-
age.
5-23
Check for continuity between the
fuel injector and the main relay.
A-15
Check for continuity between the
fuel injector and the engine ECM.
A-15
Clogged fuel injector filter Replace the fuel injector. 6-25
Engine ECM malfunction Replace the engine ECM. 7-19
Symptom 2 Cause Checking steps
See
page