1H-2 Ignition System:
No Spark or Poor Spark
B817H21804002
Troubleshooting
NOTE
Check that the transmission is in neutral and the engine stop switch is in the “RUN” position. Grasp
the clutch lever. Check that the fuse is not blown and the battery is fully-charged before diagnosing.
Spark plug quickly
becomes fouled with oil
or carbon.
Worn piston rings. Replace.
Worn pistons. Replace.
Worn cylinders. Rebore or replace.
Excessive valve-stem to valve-guide
clearance.
Replace.
Worn valve stem oil seals. Replace.
Spark plug electrodes
overheat or burn.
Incorrect spark plug (Hot type). Change to cold type spark plug.
Overheated engine. Tune-up.
Loose spark plugs. Tighten.
Excessively lean air/fuel mixture. Inspect FI system.
Condition Possible cause Correction / Reference Item
Step Action Yes No
1 Check the ignition system couplers for poor connections.
Is there connection in the ignition system couplers?
Go to step 2. Poor connection of
couplers.
2 Measure the battery voltage between input lead wires at the
ECM with the ignition switch in the “ON” position. (E02, 19:
O/G, E28: O/W)
Is the voltage OK?
Go to Step 3. • Faulty ignition switch.
• Faulty turn signal/
side-stand relay.
• Faulty engine stop
switch.
• Broken wire harness
or poor connection of
related circuit
couplers.
3 Measure the ignition coil primary peak voltage. Refer to
“Ignition Coil / Plug Cap Inspection (Page 1H-4)”.
NOTE
This inspection method is applicable only with
the multi-circuit tester and the peak volt adaptor.
Is the peak voltage OK?
Go to step 4. Go to step 5.
4 Inspect the spark plugs. Refer to “Spark Plug Inspection and
Cleaning in Section 0B (Page 0B-5)”.
Is the spark plug(-s) OK?
Go to Step 5. Faulty spark plug(-s).
5 Inspect the ignition coil/plug cap(-s). Refer to “Ignition Coil /
Plug Cap Inspection (Page 1H-4)”.
Is the ignition coil/plug cap(-s) OK?
Go to step 6. • Faulty ignition coil/
plug cap(-s).
• Poor connection of
the ignition coil/plug
cap(-s).
6 Measure the CKP sensor peak voltage and its resistance.
Refer to “CKP Sensor Inspection (Page 1H-6)”.
NOTE
The CKP sensor peak voltage inspection is
applicable only with the multi-circuit tester and
peak volt adaptor.
Is the peak voltage and resistance OK?
•Faulty ECM.
• Open or short circuit
in wire harness.
• Poor connection of
ignition couplers.
• Faulty CKP sensor.
• Metal particles or
foreign material being
stuck on the CKP
sensor and rotor tip.
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