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Fuel System Pressure Test

CAUTION: Begin fuel system trouble shooting and diagnosis with checking fuel injection system pressure. High fuel pressure may be present in fuel lines and component parts. Relieve fuel pressure before disconnecting any fuel system components.
  1. Perform On-Board Diagnostic (OBD) System Check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in TESTS W/CODES - 1.0L article. After performing OBD system check, go to next step.
  2. Relieve fuel pressure. See FUEL SYSTEM PRESSURE RELIEF . Connect negative battery cable. Install Fuel Pressure Gauge (J-34730-1A). Turn ignition on with engine off. Fuel pump should run for about 2 seconds. If fuel pressure is present, go to next step. If fuel pressure is not present, go to step 10).
  3. Turn ignition off. Turn ignition on with engine off. Fuel pump should run for about 2 seconds. Observe fuel pressure with fuel pump running. Record maximum fuel pressure. Cycle ignition on and off several times to establish an accurate reading. Fuel pressure reading should be 23-30 psi (1.6-2.1 kg/cm2 ). If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, go to step 9).
  4. Turn ignition off. Observe fuel pressure for one minute after fuel pump stops. If fuel pressure remains stable at 13 psi (0.9 kg/cm2 ) or greater, diagnose fuel pump electrical circuit. See FUEL SYSTEM ELECTRICAL CIRCUIT under NO START DIAGNOSIS . If fuel pressure does not remain stable as specified, go to next step.
  5. Check for leaking fuel injector, or fuel feed pipes and hoses. Repair as necessary. After repairs, go to step 18). If injector, and fuel feed pipes and hoses are okay, go to next step.
  6. Turn ignition on with engine off. Fuel pump should run for about 2 seconds. Pinch fuel feed hose before fuel pressure gauge and check fuel pressure. If fuel pressure remains stable at 23 psi (1.6 kg/cm2 ), go to step 17). If fuel pressure does not remain stable as specified, go to next step.
  7. Turn ignition on with engine off. Fuel pump should run for about 2 seconds. Pinch fuel return hose and check fuel pressure. If fuel pressure remains stable at 23 psi (1.6 kg/cm2 ) or greater, go to step 16). If fuel pressure does not remain stable as specified, go to next step.
  8. Check for leaking fuel injector, fuel pressure regulator or throttle body. Repair or replace as necessary. After repairs, go to step 18).
  9. If fuel pressure is less than 23 psi (1.6 kg/cm2 ), go to next step. If fuel pressure is greater than 23 psi (1.6 kg/cm2 ), go to step 13).
  10. Turn ignition on with engine off. Fuel pump should run for about 2 seconds. Pinch fuel return hose and check fuel pressure. Record maximum fuel pressure. Cycle ignition on and off several times to establish an accurate reading. If fuel pressure remains stable at 45 psi (3.2 kg/cm2 ) or greater, go to step 16). If fuel pressure does not remain stable as specified, go to next step.
  11. Check for a restricted fuel feed pipe or fuel filter. Repair as necessary. After repairs, go to step 18). If fuel feed pipe and fuel filter are okay, go to next step.
  12. Check for leaks or restrictions in fuel pump hoses and connections in fuel tank. After repairs, go to step 18). If hoses and connections are okay, go to step 17).
  13. If fuel pressure is greater than 30 psi (2.1 kg/cm2 ), go to next step.
  14. Turn ignition off. Relieve fuel pressure. See FUEL SYSTEM PRESSURE RELIEF . Disconnect fuel return hose from fuel pressure regulator. Connect a flexible hose to fuel pressure regulator and place other end in a container. Turn ignition on with engine off. Fuel pressure reading should be 23-30 psi (1.6-2.1 kg/cm2 ). If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, go to step 16).
  15. Repair or replace restricted fuel return pipe or hose. After repairs, go to step 18).
  16. Fuel pressure regulator is faulty. Replace throttle body assembly. After repairs, go to step 18).
  17. Replace fuel pump. After repairs, go to next step.
  18. Operate vehicle under conditions in which problem originally occurred. If problem no longer exists, system is okay. If problem still exists, diagnose fuel pump electrical circuit. See FUEL SYSTEM ELECTRICAL CIRCUIT under NO START DIAGNOSIS .
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