Fuel Pressure Regulator

With multipressure tester installed, and engine at normal operating temperature and idling, position adapter lever toward the fuel pump side. See Figure . Note fuel line pressure.
Fuel line pressure should be 28.4 psi (2.0 kg/cm² ). On non-turbo models, disconnect vacuum hose from pressure regulator. On turbo models, install jumper wire from Orange pressure regulator control solenoid valve to ground. See Fig 1 & Fig 2 . On all models, recheck fuel line pressure.

Fig 1: Pressure Regulator Control Solenoid Valve (Non-Turbo)
Courtesy of MAZDA MOTORS CORP.

Fig 2: Pressure Regulator Control Solenoid Valve (Turbo)
Courtesy of MAZDA MOTORS CORP.
With engine idling, fuel pressure should be approximately 34.1-39.8 psi (2.4-2.8 kg/cm² ). If not within specification, check wiring harness and pressure regulator solenoid valve. Replace pressure regulator valve if these are okay.