Suzuki GSF1250 Service Manual

1A-7 Engine General Information and Diagnosis:
Diagnostic Information and Procedures
Engine Symptom Diagnosis
B718H11104001
Condition Possible cause Correction / Reference Item
Engine will not start or is
hard to start
(Compression too low)
Valve clearance out of adjustment. Adjust.
Worn valve guides or poor seating of
valves.
Repair or replace.
Mistimed valves. Adjust.
Excessively worn piston rings. Replace.
Worn-down cylinder bores. Replace.
Starter motor cranks too slowly. Refer to “Starting System Diagram in Section
1I (Page 1I-1)”.
Poor seating of spark plugs. Retighten.
Blown cylinder head gasket. Replace.
Engine will not start or is
hard to start (Plugs not
sparking)
Fouled spark plugs. Clean.
Wet spark plugs. Clean and dry.
Defective ignition coil/plug cap. Replace.
Defective CKP sensor. Replace.
Defective ECM. Replace.
Open-circuited wiring connections. Repair or replace.
Engine will not start or is
hard to start (No fuel
reaching the intake
manifold)
Clogged fuel filter or fuel hose. Clean or replace.
Defective fuel pump. Replace.
Defective fuel pressure regulator. Replace.
Defective fuel injectors. Replace.
Defective fuel pump relay. Replace.
Defective ECM. Replace.
Open-circuited wiring connections. Check and repair.
Engine will not start or is
hard to start (Incorrect
fuel/air mixture)
Defective fuel pump. Replace.
Defective fuel pressure regulator. Replace.
Defective TP sensor. Replace.
Defective CKP sensor. Replace.
Defective IAP sensor. Replace.
Defective ECM. Replace.
Defective ECT sensor. Replace.
Defective IAT sensors. Replace.
Dirty throttle body. Clean.
Defective ISC valve. Replace.
Engine idles poorly Valve clearance out of adjustment. Adjust.
Poor seating of valves. Replace or repair.
Defective valve guides. Replace.
Worn down camshafts. Replace.
Too wide spark plug gaps. Adjust or replace.
Defective ignition coil/plug caps. Replace.
Defective CKP sensor. Replace.
Defective ECM. Replace.
Defective TP sensor. Replace.
Defective fuel pump. Replace.
Imbalanced throttle valve. Adjust.
Dirty throttle body. Clean.
Damaged or cranked vacuum hose. Replace.
Sucking air from intake pipe joint. Repair or replace.
Damaged or clogged ISC valve. Repair or replace.
ISC bad leaning.
Reset learned value.

Suzuki GSF1250 Specifications

General

Displacement	1255 cc
Bore x Stroke	79.0 mm x 64.0 mm
Compression Ratio	10.5:1
Fuel System	Fuel injection
Transmission	6-speed, constant mesh
Front Suspension	Telescopic, coil spring, oil damped
Rear Suspension	Link type, coil spring, oil damped
Front Brakes	Dual hydraulic disc
Rear Brakes	Single hydraulic disc
Front Tire	120/70ZR17M/C (58W), tubeless
Rear Tire	180/55ZR17M/C (73W), tubeless
Overall Length	2130 mm
Overall Width	790 mm
Seat Height	805 mm
Wheelbase	1485 mm
Fuel Tank Capacity	19.0 L
Starter	Electric
Final Drive	Chain
Ignition	Electronic ignition (transistorized)
Engine Type	4-stroke, liquid-cooled, DOHC
Ground Clearance	135 mm