Due to the following revisions, this bulletin supersedes bulletin 91-T-35A, which should be discarded.
0 Addition of 1993 and 1994 vehicles
0 Removal of faulty intake manifold casting surface inspection procedure
0 Revisions to diagnostic charts to simplify procedures
0 Fuel pressure specification changes in diagnostic charts
0 Removal of some service part numbers
CONDITION: Some owners of 1991-94 Saturns equipped with SOHC (LKO) engines may experience one or more of the following conditions:
0 If the vehicle is equipped with an automatic transaxle, the engine may stall after the vehicle is initially started, or stalls or stumbles when first shifted into gear.
0 If the vehicle is equipped with a manual transaxle, the engine may stall after the vehicle is initially started, when the vehicle is at a complete stop and the steering is turned to its maximum left or right position, or during launch when the engine is cold.
CAUSE: These conditions may be caused by: Loss of fuel pressure, throttle body injector (TBI) unit gasket protruding into the throttle bore (1991-1992 through VIN NZ 151498) and/or engine calibration.
0 Possible causes for the loss of the fuel pressure include the TBI fuel pressure regulator assembly valve not seating due to debris, or leaking fuel pump check valve, fuel line or injector. This condition can cause the engine to stall immediately after start, usually within 15 seconds.
0 The gasket between the TBI unit (all 1991 and 1992 engines built before and including VIN NZ151498) and intake manifold can protrude into the throttle body bore causing fuel to puddle on it.
0 The engine calibration (1991-1992 vehicles only) can cause a start/stall condition due to the calibration supplying a lean start-up fuel mixture, if the ambient temperatures are between 20-56 degrees Celsius (68-133 degrees Fahrenheit). This condition can occur during initial start and/or after the engine has been operated for one minute or more.
If the fuel system will not hold pressure, the TBI unit must be cleaned with air pressure to eliminate debris that may cause an intermittent start/stall condition. Follow the TBI unit cleaning procedures in this bulletin.
CORRECTION: If the start/stall concern is verified, proceed to the following chart to repair the concern.
---------- TBI Unit Air Pressure Cleaning Procedure (All 1991 through 1994 Saturns with SOHC [LKO] Engines)
DO NOT ALLOW SMOKING OR THE USE OF OPEN FLAMES IN THE AREA WHERE WORK ON THE FUEL SYSTEM IS TAKING PLACE. ANYTIME THE FUEL SYSTEM IS BEING WORKED ON DISCONNECT THE NEGATIVE BATTERY CABLE, EXCEPT FOR THOSE TESTS WHERE BATTERY VOLTAGE IS REQUIRED.
1. Remove fuel tank fill cap.
WHENEVER FUEL LINE FITTINGS ARE LOOSENED OR REMOVED, WRAP A SHOP CLOTH AROUND THE FITTING TO COLLECT FUEL. PLACE THE CLOTH IN AN APPROVED CONTAINER.
2. Use Gage Bar Kit SA9127E, connect the air pressure regulator to the 0-69 kPa (0 - 100 psi) pressure gage (refer to Figure).
3. Install fuel pressure test port adapter, bleed fuel into an approved container and close adapter shutoff valve. Connect hose from fuel pressure test port adapter to the air pressure regulator outlet. Refer to Figure.
4. Set air pressure regulator to zero. (Regulator shutoff valve must be open.)
5. Connect a shop air line, capable of supplying 620 kPa (90 psi) air pressure to the air pressure regulator inlet.
6. Slowly adjust air pressure to 276 kPa (40 psi) for 10 seconds and then back to zero. The air pressure will push fuel contained in the TBI unit back to the fuel tank.
7. Place a shop towel under the fuel return line connectors and remove the connectors using service tool SA9157E. Cover both openings (fuel return inlet/outlet) with shop cloths to catch debris and fuel. Refer to Figure.
8. Adjust air pressure regulator to a minimum of 414 kPa (60 psi). DO NOT exceed a maximum of 517 kPa (75 psi). Allow the fuel pressure regulator diaphragm assembly to oscillate (buzz) for one minute.
9. Set the air pressure regulator back to zero and disconnect the shop air line. Remove the air pressure regulator.
10. Install fuel return line connector. Pull back on the connector to make sure it is engaged correctly.
11. Run the engine from three to five minutes with the fuel pressure hose connected to the 0-69 kPa(0-100 psi) gage. Perform a fuel system pressure test and check fuel system leakdown. Refer to specifications provided in this bulletin and to the "Fuel/Air Intake/Exhaust Service Manual" for procedures. If the system does not pass the pressure or leakdown test, replace the fuel pressure regulator assembly or fuel pump assembly following the procedures in the "Fuel/Air Intake/Exhaust Service Manual."
12. Install fuel tank fill cap, run engine and check for fuel leaks.
1991 New Calibration (SOHC [LKO] Engines ---------------------------------------- 1309 Manual Transaxle 1312 Automatic Transaxle (Production release) 1316 Automatic Transaxle (Use when idler gear noise calibration is installed)
Only vehicles built with the latest PCM can be reprogrammed with the new calibration. Vehicles with earlier versions of the PCM require replacement of the PCM before reprogramming.
To determine if the PCM can be reprogrammed with this service calibration, check the TCM ID TABLE with the portable diagnostic tool (PDT) or the service stall system. If the TC EPROM SW ID is 4666, the PCM will have to be replaced. The new version of the PCM will have a TC EPROM SW ID of 1465.
If the PCM has to be replaced, refer to the "Powertrain Control Module" removal and installation procedures in the "Powertrain Control Module" section of the "Electronic Engine Controls Service Manual."
If the TC EPROM SW ID is 1465, refer to "Reprogramming EEPROM" in the "System Utilities" section of the "Service Stall System (SSS) User Guide" for procedures on reprogramming with the service calibration.
1992 New Calibration (SOHC [LKO] Engines) ------------------------------------------ 0740 Manual Transaxle (Production Release) 0748 Automatic Transaxle (Production release)
PARTS REQUIREMENTS: 21006914 Gasket - Throt Body 21007075 Gasket Kit -TBI Asm (Includes Diaphragm Asm)
CLAIM INFORMATION: To receive credit for this repair, submit claim through the Saturn Dealer System as follows:
Labor Case Operation Type Description Code Time ------------------------------------------------------- VW TBI Unit Gakset-Replace T9567 0.9 hrs (1991-1992 vehicles only)
VW Clean TBI Unit Pressure T9952 0.6 hrs Regulator with Air (Includes Fuel System Pressure Test)
VW TBI Pressure Regulator J5560 0.5 hrs Assembly Diaphragm -Replace (Includes Fuel System Pressure Test)
VW EC Calibration Start/Stall T9549 0.3 hrs PCM Recalibration (1991-1992 vehicles only)
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.