Engine Controls - Basic Testing: Diagnosis Suzuki X-90 I

VISUAL INSPECTION

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

Fuel Pressure Test

1. Start engine. Warm to normal operating temperature. Turn ignition off. Release fuel system pressure. See «FUEL SYSTEM PRESSURE RELEASE»(ref-26216-S29113470472001010500000). Remove plug bolt on fuel rail. Install coupling, pressure gauge and hose to fuel rail. (Scheme 1) Verify battery voltage is 11 volts or greater. Start engine and ensure no leakage exists at pressure gauge connection. Turn engine off.
2. Turn ignition on to operate fuel pump for 3 seconds. Turn ignition off. Repeat 3-4 times and check fuel pressure. See «FUEL PUMP PERFORMANCE»(ref-26216-S19422404422001010500000) and REGULATED FUEL PRESSURE tables. Start engine. Measure fuel pressure at idle. Turn ignition off.
3. If pressures are not within specification, check for defective fuel pump, pressure regulator or restriction in fuel system. See «CIRCUIT TESTS»(ref-26216-S03797831642001010500000). Repair as necessary. Remove fuel pressure gauge and start engine to ensure no fuel leakage exists.

Scheme 1

FUEL PUMP PERFORMANCE

REGULATED FUEL PRESSURE

SPARK TEST

1. Disable fuel injector(s) by disconnecting injector connector(s). Remove coil wire from distributor cap. Have a helper depress clutch pedal (M/T). Using a high output spark tester or holding coil wire terminal end 5/16" from an engine ground with an insulated holder, crank engine. Check for strong Blue spark from coil wire. If spark is not present, continue with ignition checks.
2. If spark is present at coil wire, check for spark from each spark plug wire. Remove spark plugs and connect them to spark plug wires. Ground spark plugs. If spark is present at one or more spark plug, check plug wire resistance. Using an ohmmeter, ensure resistance of each plug wire is 3000-6700 ohms per foot. Replace any plug wire that does not test as specified.

CIRCUIT TEST B-1: FUEL INJECTOR CIRCUIT INSPECTION

1. Using a mechanic's stethoscope, check each fuel injector for operating sound as engine is cranked. If all 4 fuel injectors made operating sound, system is okay. If no injectors made sound, go to next step. If one or more fuel injector(s) do not make sound, check for faulty injector harness, injector or poor connections. If injector harness, injector(s) and connections are okay, replace PCM. Retest system.
2. Turn ignition off. Disconnect harness connector from No. 1 fuel injector. Turn ignition on. Using a voltmeter, measure voltage between ground and Blue/Black wire terminal of connector. If reading is battery voltage, go to next step. If reading is not battery voltage, repair power circuit for an open or short. See «WIRING DIAGRAMS»(/suzuki/x-90/i-1995-2000/remont/wiring-diagrams-engine-performance/#wiring-diagrams) article.
3. Turn ignition off. Disconnect PCM harness connectors. On models with 3-speed automatic or manual transmission, check for continuity between PCM harness connector "C", terminal No. 12 and PCM harness connector "B", terminals No. 11, 13, 24, and 26. On models with 4-speed automatic transmission, check for continuity between PCM harness connector "A", terminal No. 3 and PCM harness connector "A", terminals No. 11, 13, 24, and 26. If continuity is not present at specified terminals, go to next step. If continuity is present at specified terminals, replace PCM. Retest system.
4. Measure resistance of each injector whose circuit did not show continuity. See «SPECIFICATIONS»(ref-26177) article for resistance specifications. Repair as necessary. If injectors are okay, replace PCM. Retest system.

CIRCUIT TEST B-2: FUEL PUMP CIRCUIT INSPECTION

1. Turn ignition on. If fuel pump is heard for 3 seconds, circuit is in good condition. If fuel pump is not heard, go to next step. CAUTION: Ensure jumper connections are made correctly. Wrong connections may result in damage to PCM and wire harness.
2. Turn ignition off. Using a fused jumper wire, backprobe Pink/Black wire and Black/White wire terminals at fuel pump relay connector located on side of heater unit inside passenger compartment. Turn ignition on. If fuel pump is heard, go to next step. If fuel pump is not heard, check Pink/Black wire or Black/White wire for an open or poor connection. Repair as necessary. If wire and connections are okay, replace fuel pump. Retest system.
3. Turn ignition off. Remove fuel pump relay. Using an ohmmeter, measure resistance between fuel pump relay terminals. (Scheme 2)or (Scheme 3). Continuity should not exist between terminals "A" and "B". On models produced in Japan, resistance between terminals "C" and "D" should be 63-77 ohms at 68°F (20°C). On models produced in Canada, resistance between terminals "C" and "D" should be 79-95 ohms at 68°F (20°C). Continuity should exist between terminals "A" and "B" as battery voltage and ground are applied to terminals "C" and "D". If resistance is as specified, go to next step. If resistance is not as specified, replace fuel pump relay. Retest system.
4. Check for poor connection or open in Pink wire or Blue/Black wire to fuel pump relay. Repair as necessary. If wire and connections are okay, replace PCM. Retest system.

Scheme 2

Scheme 3

Note. Manufacture nation can be identified by first 3 digits of VIN code.

CIRCUIT TEST B-3: FUEL PRESSURE INSPECTION

1. Check fuel pressure following procedures in «FUEL SYSTEM PRESSURE TEST»(ref-26216-S11565579572001010500000) under FUEL SYSTEM. If no fuel pressure is present, go to next step. If fuel pressure is within specification, but does not hold with ignition turned off, go to step 3). If fuel pressure is low, go to step 4). If fuel pressure is high, go to step 5).
2. Pinch fuel return hose. Turn ignition on. If fuel pressure is present, replace fuel pressure regulator. If fuel pressure is not present, fuel level is low or fuel pump circuit is at fault. Go to «CIRCUIT TEST B-2»(ref-26216-S26026659002001010500000).
3. Check for fuel leaks at fuel hoses and connections. Repair as necessary. Disconnect fuel return hose from pressure regulator. Connect a separate hose to pressure regulator and insert hose end into a container. Recheck fuel pressure. If fuel is discharged into container, replace fuel pressure regulator. If fuel does not discharge into container, check for leaking injector or fuel rail, faulty fuel pump check valve or leaking fuel pressure regulator diaphragm. Repair as necessary. Retest system.
4. Pinch fuel return hose. Turn ignition on. If fuel pressure is 56.9 psi (4 kg/cm 2 ) or greater, replace fuel pressure regulator. If fuel pressure is not as specified, check for clogged fuel filter, restricted fuel feed hose, faulty fuel pump or fuel leakage at hose connection in fuel tank. Repair as necessary. Retest system.
5. Disconnect fuel return hose from fuel pressure regulator. Connect a separate hose to pressure regulator and insert hose end into a container. Turn ignition on. If fuel pressure is within specification, repair restriction in fuel return hose. If fuel pressure is high, replace fuel pressure regulator. Retest system.

See also:
• PIN VOLTAGE CHARTS
• WIRING DIAGRAMS