Suzuki VZ800 Service Manual page 397

Complaint
Engine lacks power. Defective engine internal/electrical parts
Engine overheats
Symptom and possible causes
1. Loss of valve clearance
2. Weakened valve springs
3. Out of adjustment valve timing
4. Worn piston rings or cylinders
5. Poor seating of valves
6. Fouled spark plugs
7. Incorrect spark plugs
8. Clogged injectors
9. Out of adjustment TP sensor
10. Clogged air cleaner element
11. Imbalancing throttle valve synchronization
12. Sucking air from throttle valve or vacuum hose
13. Too much engine oil
14. Defective fuel pump or ECM
15. Defective CKP sensor and ignition coils
Defective control circuit or sensor
1. Low fuel pressure
2. Defective TP sensor
3. Defective IAT sensor
4. Defective CKP sensor
5. Defective GP sensor
6. Defective IAP sensor
7. Defective ECM
8. Out of adjustment TP sensor
9. Defective STP sensor and/or STV actuator
10. Defective EXCV actuator
Defective engine internal parts
1. Heavy carbon deposit on piston crowns
2. Not enough oil in the engine
3. Defective oil pump or clogged oil circuit
4. Sucking air from intake pipes
5. Use incorrect engine oil
6. Defective cooling system
Lean fuel/air mixture
1. Short-circuited IAP sensor/lead wire
2. Short-circuited IAT sensor/lead wire
3. Sucking air from intake pipe joint
4. Defective fuel injectors
5. Defective ECT sensor
The other factors
1. Ignition timing is too advanced due to defective
timing advance system (ECT sensor, GP sensor,
CKP sensor and ECM).
2. Drive chain is too tight.
SERVICING INFORMATION 10-9
Remedy
Adjust.
Replace.
Adjust.
Replace.
Repair.
Clean or replace.
Adjust or replace.
Clean.
Adjust.
Clean.
Adjust.
Retighten or replace.
Drain out excess oil.
Replace.
Replace.
Repair or replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Clean.
Add oil.
Replace or clean.
Retighten or replace.
Change.
See radiator section.
Repair or replace.
Repair or replace.
Clean or replace.
Repair or replace.
Replace.
Replace.
Adjust.