Honda CBR125R Owner's Manual page 97

PGM-FI SYMPTOM TROUBLESHOOTING
When the motorcycle has one of these symptoms, check the DTC or MIL blinking, refer to the DTC index (page 5-14) and
begin the appropriate troubleshooting procedure. If there are no DTC/MIL blinking stored in the ECM memory, do the diag-
nostic procedure for the symptom, in sequence listed below, until you find cause.
Symptom
Engine cranks but won't
start
(No DTC and MIL blinking)
Engine cranks but won't
start
(No fuel pump operation
sound when the turning the
ignition ON)
Engine stalls, hard to start,
rough idling
Backfiring or misfiring dur-
ing acceleration
Poor performance
(driveability) and poor fuel
economy
Idle speed is below specifi-
cations or fast idle too low
(No DTC and MIL blinking)
Idle speed is above specifi-
cations or fast idle too high
(No DTC and MIL blinking)
MIL stays ON but no DTCs
set, or MIL never comes ON
at all
MIL stays ON at all
(No DTC set)
Diagnosis procedure
1. Crank the starter for more than
ten seconds and check the DTC
(page 5-12) and execute the
troubleshooting according to
the DTC.
2. Inspect the fuel supply system
(page 5-44).
1. ECM power/ground circuits
malfunction (page 5-66).
2. Inspect the fuel supply system
(page 5-44).
1. Check the idle speed.
2. Check the IACV.
3. Inspect the fuel supply system
(page 5-44).
4. Inspect the battery charging
system (page 16-6).
Check the ignition system.
1. Inspect the fuel supply system.
2. Inspect the air cleaner element
(page 3-8).
1. Check the idle speed.
2. Check the IACV.
1. Check the idle speed.
2. Check the throttle operation
and freeplay.
3. Check the IACV.
Troubleshoot the MIL circuit (page
5-44).
Inspect the DLC circuit.
FUEL SYSTEM (PGM-FI)
Also check for
• No fuel to injector
– Clogged fuel filter
– Pinched or clogged fuel feed hose
– Faulty fuel pump
– Faulty fuel pump circuits
• Intake air leak
• Contaminated/deteriorated fuel
• Faulty fuel injector
• IACV stuck
• Faulty ignition system
• Open circuit in the power input and/or
ground wire of the ECM
• Blown main fuse (30 A)
• Blown sub fuse (10 A)
• Restricted fuel feed hose
• Contaminated/deteriorated fuel
• Intake air leak
• Faulty IACV
• Restricted fuel tank breather hose
• Faulty ignition system
• Faulty battery charging system
• Faulty ignition system
• Pinched or clogged fuel feed hose
• Faulty pressure regulator (fuel pump)
• Faulty injector
• Faulty ignition system
• Clogged air cleaner element
• IACV stuck closed
• Faulty fuel supply system
• Faulty ignition system
• IACV stuck opened
• Faulty ignition system
• Intake air leak
• Engine top-end problem
• Air cleaner element condition
• Faulty MIL circuit
• Short circuit in the DLC related wire
5-5