SMU-SECTION 6E2-REVISED FUEL PRESSURE SPECS.. Geo Metro 1993

SUBJECT: SERVICE MANUAL UPDATE-SECTION 6E2-REVISED FUEL PRESSURE SPECIFICATIONS

MODELS: 1989-94 GEO METRO WITH 1.0L ENGINE (VIN 6 - RPO LP2)

CIRCUIT DESCRIPTION: WHEN THE IGNITION SWITCH IS TURNED TO THE "ON" POSITION, THE ENGINE CONTROL MODULE (ECM) WILL TURN "ON" THE IN-TANK FUEL PUMP. IT WILL REMAIN "ON" AS LONG AS THE ENGINE IS CRANKING OR RUNNING AND THE ECM IS RECEIVING IGNITION REFERENCE PULSES. IF THERE ARE NO REFERENCE PULSES, THE ECM WILL SHUT "OFF" THE FUEL PUMP IN ABOUT 2 SECONDS AFTER IGNITION "ON" OR ENGINE STOPS.

THE FUEL PUMP DELIVERS FUEL THROUGH AN IN-LINE FILTER TO THE TBI ASSEMBLY. THE INTEGRAL FUEL PRESSURE REGULATOR CONTROLS SYSTEM PRESSURE TO ABOUT 160-210 KPA (23-31 PSI) WITH IGNITION SWITCH "ON" AND TO ABOUT 90-140 KPA (13-20 PSI) WITH THE ENGINE IDLING AT NORMAL OPERATING TEMPERATURE. EXCESS FUEL IS RETURNED TO THE FUEL TANK THROUGH A SEPARATE LINE.

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GENERAL MOTORS BULLETINS ARE INTENDED FOR USE BY PROFESSIONAL TECHNICIANS, NOT A "DO-IT-YOURSELFER". THEY ARE WRITTEN TO INFORM THOSE TECHNICIANS OF CONDITIONS THAT MAY OCCUR ON SOME VEHICLES, OR TO PROVIDE INFORMATION THAT COULD ASSIST IN THE PROPER SERVICE OF A VEHICLE. PROPERLY TRAINED TECHNICIANS HAVE THE EQUIPMENT, TOOLS, SAFETY INSTRUCTIONS AND KNOW-HOW TO DO A JOB PROPERLY AND SAFELY. IF A CONDITION IS DESCRIBED, DO NOT ASSUME THAT THE BULLETIN APPLIES TO YOUR VEHICLE, OR THAT YOUR VEHICLE WILL HAVE THAT CONDITION. SEE A GENERAL MOTORS DEALER SERVICING YOUR BRAND OF GENERAL MOTORS VEHICLE FOR INFORMATION ON WHETHER YOUR VEHICLE MAY BENEFIT FROM THE INFORMATION.