Test NS-2A - Checking Fuel System

NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION . For appropriate wiring diagram, see WIRING DIAGRAMS at end of article. article.

Turn ignition on. Remove fuel tank filler cap. Using DRB-II, actuate fuel pump. Listen for fuel pump operating sound at fuel tank filler pipe. If fuel pump is not operating, perform TEST NS-3A. High fuel pressure may be present in fuel lines. Open fuel system with caution. See FUEL PRESSURE RELEASE .
If fuel pump is operating, turn ignition off. Disconnect fuel pump connector at fuel tank. Crank engine for 10 seconds. Turn ignition off. Disconnect negative battery cable. Release fuel pressure. Connect fuel pressure gauge and adapter to fuel rail. Reconnect negative battery cable and fuel pump connector at fuel tank.
Connect jumper wire between battery positive terminal and single-wire fuel pump check connector Black/White wire, located near battery in engine compartment. Ensure no fuel leaks are present.
Read fuel pressure gauge. If fuel pressure is not 38-50 psi (2.7-3.5 kg/cm² ), go to next step. If fuel pressure is 38-50 psi (2.7-3.5 kg/cm² ), disconnect jumper wire. Remove and inspect spark plugs. If spark plug tips are wet, clean and dry plugs. Install spark plugs, and perform TEST VER-1. If spark plug tips are dry, check engine for mechanical failure (i.e., valve timing and engine compression). Repair as necessary, and perform TEST VER-1.
If fuel pressure is less than 38 psi (3.5 kg/cm² ), go to next step. If fuel pressure is more than 50 psi (3.5 kg/cm² ), inspect for restricted fuel return line, and repair as necessary. Perform TEST VER-1. If fuel return line is not restricted, replace fuel pressure regulator. Perform TEST VER-1.
CAUTION: DO NOT allow fuel pressure to exceed 60 psi when squeezing fuel return hose.
Squeeze fuel return hose, and check pressure. If fuel pressure is more than 38 psi (2.7 kg/cm² ), replace fuel pressure regulator. Perform TEST VER-1. If fuel pressure is less than 38 psi (2.7 kg/cm² ), remove jumper wire from fuel pump check connector. Stop squeezing fuel return hose. Inspect fuel supply line for restriction.
If restriction exists in fuel supply line, repair as necessary. Perform TEST VER-1. If there is no restriction in fuel supply line, disconnect fuel pump electrical connector at fuel tank. Crank engine until fuel pressure gauge reads zero psi.
Disconnect fuel filter. Inspect fuel filter for restriction. If fuel filter is restricted, replace fuel filter. Perform TEST VER-1. If fuel filter is not restricted, replace fuel pump. Perform TEST VER-1.