Engine Controls - Basic Testing: Diagnosis Honda Civic V

VISUAL INSPECTION

Visually inspect all electrical wiring, for chafed, stretched, cut or pinched wiring. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and not pinched or cut. See VACUUM DIAGRAMS article in this section to verify routing and connections. Inspect air induction system for possible vacuum leaks.

Basic Diagnosis

Basic diagnosis of fuel system should begin with determining fuel system pressure. If fuel pump fails to run on fuel-injected models, inspect power supply to main relay. If all power supplies are present (i.e. battery, ignition and starter switch during cranking), perform functional test of main relay. See WIRING DIAGRAMS and SYSTEM/COMPONENT TESTS articles in this section.

Scheme 17

1. Disconnect negative battery cable. Relieve fuel pressure. See «RELIEVING FUEL PRESSURE»(ref-15742-S15042441562001010800000). Connect Fuel Pressure Gauge (07406-0040001 ) at 6-mm bolt. Reconnect negative battery cable. Start engine, and note fuel pressure. If vehicle will not start, check for spark. If spark is present and no fuel pressure is evident, inspect fuel pump main relay.
2. Remove connector from fuel pump main relay. (Scheme 17) Using a test light, check for power on Black/Yellow wire at fuel pump relay connector. If power is present, connect a jumper wire between Black/Yellow wire (B+) and Yellow/Black wire. If fuel pump runs, proceed to step 3). If fuel pump fails to run, see «SYSTEM/COMPONENT TESTS»(ref-15662) article in this section. If no voltage is present on the Black/Yellow wire, check for open in wire between fuel pump main relay connector and No. 2 fuse on fuse box. Proceed to step 3) after repairing circuit.
3. Start engine. Disconnect vacuum hose from pressure regulator and check for manifold vacuum. If vacuum is not present, check for restriction in vacuum port or hose. Plug vacuum hose and inspect fuel pressure gauge reading. Gauge reading should be within specification. See «FUEL PRESSURE»(ref-15742-S31101997712001010800000) table. Pressure should drop slightly when vacuum hose is reconnected. FUEL PRESSURE (1) Application At Idle psi (kg/cm 2 ) Civic 36-37 (2.50-2.60) CRX 35-41 (2.45-2.90) (1) Fuel pressure is tested with vacuum hose removed from pressure regulator.
4. If pressure is higher than specified, inspect for pinched or clogged fuel return line between fuel rail and fuel tank. If no problem is found in fuel line, replace pressure regulator.
5. If pressure is lower than specified, inspect for plugged fuel filter. If filter is not plugged, lightly pinch fuel return line. If fuel pressure does not rise, replace fuel pump. If fuel pressure rises, replace pressure regulator. NOTE: If vehicle starts and runs, fuel pump main relay is okay.

See also:
• WIRING DIAGRAMS