Fuel Pressure
Begin basic diagnosis of fuel system by determining fuel system pressure. If fuel pump is inoperative, check fuel pump fuse. If fuse is okay, see FUEL SYSTEM in SYSTEM/COMPONENT TESTS article in the ENGINE PERFORMANCE section. See WIRING DIAGRAMS at the end of this article for specific circuit or wire color.
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 it to run until it stalls. Crank engine 2 or 3 more times to verify all pressure has dissipated.
- Turn ignition off. Install fuel pump fuse or relay. Connect fuel gauge between fuel filter outlet and fuel tube using a "T" connector. Disconnect electrical connector at fuel pressure regulator control solenoid valve (if equipped).
- Start engine. Check fuel line connections for leaks. Check fuel pressure with engine idling. Disconnect vacuum hose from pressure regulator. 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.
FUEL PRESSURE
| Application | At Idle W/O Vacuum psi (kg/cm2 ) | At Idle W/ Vacuum psi (kg/cm2 ) |
|---|---|---|
| Sentra | 43 (3.0) | 36 (2.5) |