Edmunds Answers

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  • avatar karjunkie 11/07/08 3:59 pm PST

    This test checks the operation of the fuel pressure regulator to make sure it changes line pressure in response to changes in engine vacuum. This is necessary to maintain the proper operating pressure behind the injectors and to compensate for changes in engine load. With the engine running, disconnect the vacuum hose from the pressure regulator. As a rule, fuel system pressure should increase 8 to 12 psi with the line disconnected. You are only 6 psi more, so I suspect you have a leaking diaphragm in the regulator If the diaphragm inside the regulator is leaking, engine vacuum will suck raw fuel into the intake manifold through the vacuum hose, so look for fuel inside the hose as this will confirm your suspicion.

Answers

  • karjunkie 11/07/08 3:59 pm PST

    This test checks the operation of the fuel pressure regulator to make sure it changes line pressure in response to changes in engine vacuum. This is necessary to maintain the proper operating pressure behind the injectors and to compensate for changes in engine load. With the engine running, disconnect the vacuum hose from the pressure regulator. As a rule, fuel system pressure should increase 8 to 12 psi with the line disconnected. You are only 6 psi more, so I suspect you have a leaking diaphragm in the regulator If the diaphragm inside the regulator is leaking, engine vacuum will suck raw fuel into the intake manifold through the vacuum hose, so look for fuel inside the hose as this will confirm your suspicion.

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