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Home >> Mazda >> 1992 >> 929 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Testing >> Fuel System >> Fuel Pressure (Fuel Injection) >> Fuel Pressure
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Fuel Pressure

  1. Disconnect circuit opening relay. See CIRCUIT OPENING RELAY LOCATIONS  table.
  2. To bleed down fuel in system, start engine (if possible) and allow to die. Connect pressure gauge to fuel line at fuel filter. Reconnect circuit opening relay.
  3. On Navajo, install EFI Pressure Gauge (T80L-9974-B) to relief valve. Relief valve is located on fuel supply manifold.
  4. Turn ignition on. Using a jumper wire, connect terminals of Yellow fuel pump check connector together. See FUEL PUMP CHECK CONNECTOR (YELLOW) LOCATIONS  table. On Miata, MX-3, Protege, 323 and 929, jump test connector terminals Fp and ground. If pump runs, check fuel pump circuit and circuit opening relay.
    FUEL PUMP CHECK CONNECTOR (YELLOW) LOCATIONS

    Application Location
    B2600i, Miata, MX-6, 323 & 626 On Firewall, Near Windshield Wiper Motor
    MPV Near Airflow Sensor
    Navajo At Right Inner Fender Panel
  5. If possible, start engine. Check fuel pressure with vacuum connected to and disconnected from pressure regulator. See REGULATED FUEL PRESSURE (FUEL INJECTION)  table. Turn engine off and disconnect jumper wire at fuel pump check connector. Wait 10 minutes and ensure residual pressure is at least 21 psi (1.5 kg/cm2 ).
  6. Operate fuel pump by jumpering fuel pump test connector. Check fuel pump performance. Pinch hose between pressure gauge and fuel filter. DO NOT  hold longer than necessary to check pressure. See the FUEL PUMP PERFORMANCE table below. If pump does not meet specifications, check fuel pump circuits, fuel pump, fuel tank, fuel filter or replace fuel pump.
FUEL PUMP PERFORMANCE

Application Pressure
Navajo (1)
All Others (2) 64-92 psi (4.5-6.5 kg/cm2 )
(1) Information is not available.
(2) Minimum volume in 30 seconds is 1.0 pint (.47L).
REGULATED FUEL PRESSURE (FUEL INJECTION)

Application At Idle W/ Vacuum psi (kg/cm2 ) At Idle W/O Vacuum psi (kg/cm2 )
B2200 (PFI) & B2600i 28-37 (2.0-2.6) 38-46 (2.7-3.2)
Miata 31-38 (2.2-2.7) 38-46 (2.7-3.2)
MPV 30-37 (2.1-2.6) 38-46 (2.7-3.2)
MX-3, Protege & 323 30-37 (2.1-2.6) 38-46 (2.7-3.2)
MX-6 & 626 27-33 (1.9-2.3) 34-40 (2.4-2.8)
Navajo (1) (2)
929 31-38 (2.2-2.7) 38-46 (2.7-3.2)
(1) Pressure should be 30-45 psi (2.2-3.2 kg/cm2 ) with engine running and 35-45 psi (2.5-3.2 kg/cm2 ) with key on and engine off.
(2) Information is not available.
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