Suzuki VLR1800, Service Manual

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Engine General Information and Diagnosis: 1A-10
Noisy engine (Noise
seems to come from
water pump) Too much play on pump shaft bearing. Replace.
Worn or damaged impeller shaft. Replace.
Worn or damaged mechanical seal. Replace.
Contact between pump case and
impeller. Replace.
Engine runs poorly in
high speed range
(Defective engine internal/
electrical parts) Weakened valve spring. Replace.
Worn camshafts. Replace.
Valve timing out of adjustment. Adjust.
Too narrow spark plug gaps. Adjust.
Ignition not advanced sufficiently due to
poorly working timing advance circuit. Replace ECM.
Defective ignition coils. Replace.
Defective ignition coil/plug caps. Replace.
Defective CKP sensor. Replace.
Defective ECM. Replace.
Clogged air cleaner element. Clean.
Clogged fuel hose, resulting in
inadequate fuel supply to injector. Clean and prime.
Defective fuel pump. Replace.
Defective TP sensor. Replace.
Defective STP sensor or STVA. Replace.
Engine runs poorly in
high speed range
(Defective air flow
system) Clogged air cleaner element. Clean or replace.
Defective throttle valve. Adjust or replace.
Defective secondary throttle valve. Adjust or replace.
Sucking air from throttle body joint. Repair or replace.
Defective ECM. Replace.
Imbalancing throttle valve
synchronization. Adjust.
Defective STP sensor or STVA. Replace.
Engine runs poorly in
high speed range
(Defective control circuit
or sensor) Low fuel pressure. Repair or replace.
Defective TP sensor. Replace.
Defective IAT sensors. Replace.
Defective CKP sensor. Replace.
Defective GP sensor. Replace.
Defective IAP sensors. Replace.
Defective ECM. Replace.
TP sensor out of adjustment. Adjust.
Defective STP sensor and/or STVA. Replace.
Defective EXCVA or STVA. Replace.
Engine lacks power
(Defective engine internal/
electrical parts) Loss of valve clearance. Adjust.
Weakened valve springs. Replace.
Valve timing out of adjustment. Adjust.
Worn piston rings or cylinders. Replace.
Poor seating of valves. Repair.
Fouled spark plugs. Clean or replace.
Incorrect spark plugs. Adjust or replace.
Clogged fuel injectors. Replace.
TP sensor out of adjustment. Adjust.
Clogged air cleaner element. Replace.
Imbalancing throttle valve
synchronization. Adjust.
Sucking air from throttle valve or
vacuum hose. Retighten or replace.
Too much engine oil. Drain out excess oil.
Defective fuel pump or ECM. Replace.
Defective CKP sensor and ignition coils. Replace.
Defective STP sensor or STVA. Replace.
Condition Possible cause Correction / Reference Item