Fuel Line Pressure Inspection
- Disconnect negative battery cable. Release fuel pressure. See FUEL PRESSURE RELEASE . Install fuel pressure gauge in fuel supply line. On all models except 626, Reconnect negative battery cable and go to next step. On 626, go to step 3 .
- Locate DLC-1 on left side of engine compartment. Connect a fused jumper wire between DLC-1 terminals F/P and GND. See Figure . Turn ignition switch on and observe fuel line pressure. See FUEL LINE PRESSURE table.
- Locate and remove fuel pump relay. See FUEL PUMP RELAY LOCATIONS table. Connect fused jumper wire between ground and fuel pump relay socket terminal No. 30. See Figure . Reconnect negative battery cable, to operate fuel pump. Observe fuel line pressure. See FUEL LINE PRESSURE table.
- If fuel line pressure is high, check for plugged return line. If no problem is found, replace fuel pressure regulator. If fuel line pressure is low, check fuel pump maximum pressure. See FUEL PUMP MAXIMUM PRESSURE INSPECTION . If fuel pump maximum pressure is as specified, check for plugged or restricted fuel line or fuel filter. Repair as necessary. If no problems are found, replace pressure regulator.
FUEL LINE PRESSURE
| Application | Pressure psi (kg/cm2 ) | |
|---|---|---|
| Miata | 53-61 (3.7-4.3) | |
| Millenia | ||
| 2.3L | 41-48 (2.9-3.4) | |
| 2.5L | 39-45 (2.7-3.2) | |
| MPV | 55-61 (3.9-4.3) | |
| Protege & Protege5 | 39-45 (2.7-3.2) | |
| 626 | ||
| 2.0L | 37-46 (2.6-3.3) | |
| 2.5L | 39-45 (2.7-3.2) | |