KN4 - Check Vacuum Signal Between FPRC Solenoid and Manifold
- Key "OFF".
- Tee in a standard vacuum gauge at the hose between the manifold vacuum source and the Fuel Pressure Regulator Control (FPRC) solenoid input vacuum port.
- Start and idle engine while observing the vacuum gauge needle.
- Was a vacuum signal present?
Yes -- Remove vacuum gauge. Go to KN5. KN5 - Check Vacuum Between FPRC Solenoid and FPR
No -- Address base engine vacuum source concern.