Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSMAZDA1997MILLENIA V6-2.5L DOHCREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSFUEL TANK PRESSURE SENSORTESTING AND INSPECTION
1997 Mazda Millenia V6-2.5L DOHC
Fuel Tank Pressure Sensor: Testing and Inspection
1997 Mazda Millenia V6-2.5L DOHCSECTION Testing and Inspection
FUEL TANK PRESSURE SENSOR TESTING
NOTE: The following vacuum and pressure values are indicated by relative pressure from atmospheric pressure.
1. Connect the Special Service Tools (Engine Signal Monitor) to the PCM as shown.
CAUTION: Do not apply a vacuum or pressure outside of the specified limits. Doing so will damage the fuel tank pressure sensor.
2. Apply pressure then a vacuum to the fuel tank pressure sensor according to the following procedure.
3. Decrease the applied pressure from +6.66 kPa (+50 mmHg, +1.97 in.Hg) to -6.66 kPa (-50 mmHg, -1.97 in.Hg) and verify that the PCM terminal 3F voltage decreases accordingly.
NOTE: The output voltage varies with the measuring condition.
- Input voltage - 5.0 V
- Atmospheric pressure - 101.3 kPa (29.9 in.Hg)
- Outside temperature - 30-100°C (0-182°F)
4. If not as specified inspect harness continuity:
- Between PCM terminal 3U and fuel tank pressure sensor terminal A
- Between PCM terminal 3AB and fuel tank pressure sensor terminal B
- Between PCM terminal 3A and fuel tank pressure sensor terminal C
Terminal voltage
- Fuel tank pressure sensor terminal B voltage: Ground (Below 1.0 V)
- Fuel tank pressure sensor terminal C voltage: Constant voltage (4.5-5.5 V)
5. If terminal voltage is correct and if there is harness continuity, replace the fuel tank pressure sensor.
NOTE: The following vacuum and pressure values are indicated by relative pressure from atmospheric pressure.
1. Connect the Special Service Tools (Engine Signal Monitor) to the PCM as shown.
CAUTION: Do not apply a vacuum or pressure outside of the specified limits. Doing so will damage the fuel tank pressure sensor.
2. Apply pressure then a vacuum to the fuel tank pressure sensor according to the following procedure.
3. Decrease the applied pressure from +6.66 kPa (+50 mmHg, +1.97 in.Hg) to -6.66 kPa (-50 mmHg, -1.97 in.Hg) and verify that the PCM terminal 3F voltage decreases accordingly.
NOTE: The output voltage varies with the measuring condition.
- Input voltage - 5.0 V
- Atmospheric pressure - 101.3 kPa (29.9 in.Hg)
- Outside temperature - 30-100°C (0-182°F)
4. If not as specified inspect harness continuity:
- Between PCM terminal 3U and fuel tank pressure sensor terminal A
- Between PCM terminal 3AB and fuel tank pressure sensor terminal B
- Between PCM terminal 3A and fuel tank pressure sensor terminal C
Terminal voltage
- Fuel tank pressure sensor terminal B voltage: Ground (Below 1.0 V)
- Fuel tank pressure sensor terminal C voltage: Constant voltage (4.5-5.5 V)
5. If terminal voltage is correct and if there is harness continuity, replace the fuel tank pressure sensor.
RENDER: 1.0x
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.