Symptom Troubleshooting - Honda TRX680FA Service Manual

FUEL SYSTEM (PGM-FI)
SYMPTOM TROUBLESHOOTING
When the vehicle has one of these symptoms, check the DTC or MIL blinking, refer to the DTC index (page 6-17) and begin
the appropriate troubleshooting procedure. If there are no DTC/MIL blinking stored in the PCM memory, do the diagnostic
procedure for the symptom, in the sequence listed below, until you find the 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 and engine stop
switch "O")
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 times
(No DTC set)
Diagnosis procedure
1. Inspect the ignition system
(page 21-5).
2. Inspect the fuel supply system
(page 6-36).
1. PCM power/ground circuits
malfunction (page 6-53)
2. Inspect the fuel supply system
(page 6-36).
1. Check the idle speed (page 6-
55).
2. Check the IACV (page 6-56).
3. Inspect the fuel supply system
(page 6-36).
Check the ignition system.
Inspect the fuel supply system
(page 6-36).
1. Check the idle speed (page 6-
55)
2. Check the IACV (page 6-56).
1. Check the idle speed (page 6-
55)
2. Check the throttle operation
and lever free play (page 4-4)
3. Check the IACV (page 6-56).
Troubleshoot the MIL circuit (page
6-31).
Check the DLC circuit (Brown/red
wire) for short circuit.
Also check for
4
4
» No fuel to injector
- Clogged fuel filter
- Pinched or clogged fuel feed hose
- Pinched or clogged fuel tank breather
hose
- Faulty fuel pump
- Faulty fuel pump circuits
1
Intake air leak
» Contaminated/deteriorated fuel
» Faulty fuel injector
• IACV stuck closed
• Open circuit in the power input and/or
ground wire of the PCM
> Faulty bank angle sensor or related circuit
> Faulty engine stop relay or related circuit
> Faulty engine stop switch or related circuit
« BlownFI/IGNfuse(10A)
> BlownST./ECMfuse(10A)
> Restricted fuel feed hose
> Contaminated/deteriorated fuel
• Intake air leak
• Restricted fuel tank breather hose
• Faulty ignition system
• Faulty ignition system
> Pinched or clogged fuel feed hose
> Faulty injector
> Faulty ignition system
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 condition
• Faulty MIL circuit
• Short circuit in the DLC related wire
6-5