TBI Unit Air Pressure Cleaning Procedure
(All 1991 through 1994 Saturns with SOHC [LKO] Engines)CAUTION:
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.
CAUTION:
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 Gauge Bar Kit SA9127E, connect the air pressure regulator to the 0-690 kPa (0 - 100 psi) pressure gauge. 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 connect and remove the connect 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.
IMPORTANT:
If the fuel pressure diaphragm does not oscillate (buzz), use service tool SA9106E (MFI Throttle Body Minimum Air Tool) and momentarily plug the steel fuel return line opening. The plug may have to be inserted and removed several times until the diaphragm begins to oscillate (buzz). If the diaphragm will not oscillate, replace the diaphragm assembly following the procedures in the "Fuel/Air Intake/Exhaust Service Manual." After the fuel pressure regulator valve has been replaced, test the fuel system again.
9. Set the air pressure regulator back to zero and disconnect the shop air line. Remove the air pressure regulator.
NOTICE:
Whenever fuel line connects are disconnected, lubricate steel line male ends with clean engine oil. Holding steel line, firmly press on female connector until click is heard, then pull back to confirm engagement. Make sure the fuel line connects are fully seated. Pinched, kinked or damaged fuel lines must be replaced.
10. Install fuel return line connect. Pull back on the connect to make sure it is engaged correctly.
11. Run the engine from three to five minutes with the fuel pressure hose connected to the
0-690 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.