Fuel Pressure Regulator Inspection

Disconnect negative battery cable. Release fuel pressure. See FUEL PRESSURE RELEASE . Install fuel pressure gauge in fuel supply line. Reconnect negative battery cable.
Start and operate engine at idle. Ensure vacuum is available to pressure regulator. Observe fuel pressure with vacuum hose connected and disconnected at fuel pressure regulator. See REGULATED FUEL PRESSURE table. If fuel pressure is not as specified, replace fuel pressure regulator.

REGULATED FUEL PRESSURE

Application

At Idle W/Vacuum psi (kg/cm² )

At Idle W/O Vacuum psi (kg/cm² )

Miata

⁽¹⁾

Millenia

2.3L

30-41 (2.1-2.9)

40-48 (2.8-3.4)

2.5L

30-38 (2.1-2.7)

38-46 (2.7-3.2)

MPV

⁽¹⁾

Protege & Protege5

30-37 (2.1-2.6)

38-46 (2.7-3.2)

626

2.0L

30-38 (2.1-2.7)

37-47 (2.6-3.3)

2.5L

30-37 (2.1-2.6)

38-46 (2.7-3.2)

⁽¹⁾	Due to the adoption of the mechanical returnless fuel system, the pressure regulator cannot be inspected separately. Perform Fuel Line Pressure test.