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Engine Controls - Basic Diagnostic Procedures: Diagnosis Subaru Forester SG

Testing & Diagnostics 1 illustration ~172 words

VISUAL INSPECTION

Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and are not pinched or cut. See VACUUM DIAGRAMS article to verify vacuum hose routing and connections (if necessary). Inspect air induction system for possible vacuum leaks.

MECHANICAL INSPECTION

Note. When using screw-in type compression gauge to measure cylinder compression pressure, ensure threaded end is less than 0.71" (18 mm) long.

Note. Engine vacuum information is not available from manufacturer for 3.0L engine.

NO-START DIAGNOSIS

CAUTIONEnsure proper starting procedures are employed if vehicle is equipped with anti-theft system.

Scheme 1

Scheme 1

FUEL PRESSURE TEST

Note. For information on testing individual fuel system components, see FUEL SYSTEMS in SYSTEM & COMPONENT TESTING article.

Relieve fuel pressure. See FUEL SYSTEM PRESSURE RELEASE . Remove fuel filler cap. Disconnect fuel delivery hoses from fuel filter, and install fuel pressure gauge. Install fuel filler cap. Start engine and check fuel pressure at idle. See FUEL PRESSURE AT IDLE table.

ApplicationVacuum Line Connected psi (kg/cm 2 )Vacuum Line Disconnected psi (kg/cm 2 )
All Models(1) 30-34 (206-235)(1) 41-46 (284-314)
(1) Fuel pressure readings will be 1-3 psi (0.1-0.2 kg/cm 2 ) higher at high altitudes.
(1)Fuel pressure readings will be 1-3 psi (0.1-0.2 kg/cm 2 ) higher at high altitudes.

FUEL PRESSURE AT IDLE