Fuel Pressure
Basic diagnosis of fuel system should begin with determining fuel system pressure. If fuel pump is inoperative, check fuel pump fuse in fuse panel. If fuse is okay, see FUEL PUMP and FUEL PUMP RELAY charts in SYSTEM/COMP TESTS article. See L - WIRING DIAGRAMS article for specific circuit or wire color reference.
WARNING:
ALWAYS relieve fuel pressure before disconnecting any fuel injection-related component. DO NOT allow fuel to contact engine or electrical components. If connecting fuel pressure gauge to fuel system without using a "T" connector, DO NOT operate fuel pump for more than a few seconds. Operating fuel pump longer than a few seconds under this condition can damage fuel pump.
- To relieve fuel system pressure, remove fuel pump fuse. Start engine and allow to run until fuel is exhausted and engine stalls. Crank engine an additional 2 or 3 times to verify all pressure has dissipated. Turn ignition off. Install fuel pump fuse.
- On Axxess, Maxima, Pickup (4-cylinder), Stanza and 240SX, connect fuel gauge between fuel filter and pressure regulator.
- On Pathfinder, Pickup (V6) and 300ZX, connect fuel gauge between fuel filter outlet and fuel tube.
- On Pulsar NX, Sentra and Van, disconnect fuel inlet hose at fuel injection throttle body.
- On all models, install fuel pressure gauge using a "T" connector. To prevent inaccurate fuel pressure readings, disconnect electrical connector at fuel pressure regulator control solenoid valve (if equipped). Start engine and check fuel line connections for leaks.
- Check fuel pressure on pressure gauge with engine idling. Disconnect vacuum hose from pressure regulator and recheck fuel pressure. Compare fuel pressure readings on pressure gauge with specifications in FUEL PRESSURE table.
- Release fuel system pressure as described in step 1). Disconnect fuel pressure gauge. Reconnect fuel lines. Start engine and check for fuel leaks. If necessary, clear trouble code 22 from ECU memory.
FUEL PRESSURE SPECIFICATION - psi (kg/cm2
)
| Application | Unregulated (w/o Vacuum) | Regulated (w/Vacuum) | ||
|---|---|---|---|---|
| Axxess & 240SX | 43 (3.0) | 33 (2.3) | ||
| Maxima & 300ZX | 43 (3.0) | 36 (2.5) | ||
| Pathfinder & Pickup | 43 (3.0) | 33 (2.3) | ||
| Pulsar NX & Sentra | (1) | 34 (2.4) | ||
| Stanza | 43 (3.0) | 33 (2.3) | ||
| Van | (1) | 36 (2.5) | ||
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