Fuel Pressure Check

Fig. 419 Connecting battery to fuel pump terminals.:

Fig. 420 Connecting battery to fuel pump terminals.:

1. Release fuel system pressure.
2. Disconnect fuel hose between fuel filter and fuel tube on engine side.
3. Install fuel pressure gauge J-2540034 or equivalent between fuel filter and fuel tube.
4. Start engine and check for fuel leaks, then check pressure gauge reading.
5. At idle, fuel pressure should be approximately 30-37 psi. At the moment the accelerator pedal is fully depressed, fuel pressure reading should be approximately 37-44 psi.
6. Place ignition switch in the Off position, then disconnect fuel pressure regulator vacuum hose from intake collector. Plug collector with a rubber cap.
7. Connect variable vacuum source J-23738 or equivalent to fuel pressure regulator.
8. On 1985-86 models, disconnect fuel pump wire connector and apply battery voltage to pump terminals, Figs. 419 and 420.
9. On 1987-88 Maxima, 200SX and 300ZX, jump No. 108 connector of ECU to body ground.
10. On all models, start engine and note fuel pressure readings as vacuum is changed. Fuel pressure decreases as vacuum increases. Fuel pressure should be 36-37 psi at 0 inch Hg vacuum, 33-35 psi at 5 inches, 31-32 psi at 10 inches, 29-30 psi at 15 inches and 26-28 psi at 20 inches.
11. If the above test results are unsatisfactory, replace fuel pressure regulator.
12. Release fuel system pressure, then reconnect vacuum line, fuel hose and fuel pump wire connector. When reconnecting fuel hose, use a new clamp, ensuring clamp is properly positioned.