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Test 9: Fuel Pressure Regulator

TEST 9: FUEL PRESSURE REGULATOR

TEST 9 FUEL PRESSURE REGULATOR
STEP  INSPECTION  ACTION 
1 CHECK FUEL PRESSURE
WARNING: Before performing the following operation, release the fuel pressure from the fuel system to reduce the possibility of injury or fire.
  • Connect fuel pressure gauge, 49UN01010.
  • Start engine and run at idle.
  • Disconnect the vacuum hose from the fuel pressure regulator and plug it.
  • Drive vehicle under heavy acceleration while observing fuel pressure gauge reading.
  • Does fuel pressure hold steady within 20.6 kPa (3 psi)? 
 Yes Go to step 2.
No Check fuel vapor valve. If OK, check for clogged fuel filter.
2 CHECK FUEL PRESSURE WITH VACUUM APPLIED TO REGULATOR
  • Connect vacuum pump to the fuel pressure regulator.
  • Apply vacuum to fuel pressure regulator.
  • Does fuel line pressure decrease when vacuum is applied? 
 Yes Check vacuum hose and vacuum source.
Repair or replace as necessary.
Go to step 3.
No Replace fuel pressure regulator.
Go to step 4.
3 CHECK FUEL PRESSURE AND VERIFY FUEL FLOW
  • Disconnect the fuel return line from the fuel rail.
  • Connect a short hose from the fuel rail to a one liter (one quart) measuring container.
  • Key ON, Engine OFF (KOEO).
  • Connect NGS Tester to the DLC and select Active Command Mode.
  • Select OUTPUT TEST MODE.
  • Press MODE to change to the "ALL ON" mode, and press start to run fuel pump.
  • Measure fuel line pressure and verify fuel is flowing into container.
  • Is fuel pressure still high? 
 Yes Replace fuel pressure regulator.
Restore vehicle.
No Inspect fuel return line for blockage or clog.
Repair or replace as necessary.
Go to step 4.
4 CHECK REGULATOR FOR FUEL LEAKS
  • Start engine and run at idle for 10 seconds.
  • Turn the ignition OFF for 10 seconds.
  • Start engine and run at idle for 10 seconds.
  • Turn ignition switch OFF.
  • Disconnect the vacuum hose from the pressure regulator.
  • Is the diaphragm leaking fuel? 
 Yes Replace fuel pressure regulator.
Restore vehicle.
No Restore vehicle.
Test end.
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