Engine Controls - Basic Diagnostic Procedures: Diagnosis Mazda Tribute 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 possible vacuum leaks.

Fuel Line Pressure Inspection

1. Disconnect negative battery cable. Release fuel pressure. See «FUEL PRESSURE RELEASE»(ref-134958-S02405930982002022100000). Install fuel pressure gauge in fuel supply line. On all models except 626, Reconnect negative battery cable and go to next step. On 626, go to step 3.
2. Locate DLC-1 on left side of engine compartment. Connect a fused jumper wire between DLC-1 terminals F/P and GND. see scheme 2 Turn ignition switch on and observe fuel line pressure. See «FUEL LINE PRESSURE»(ref-134958-S10088893632002022100000) table.
3. Locate and remove fuel pump relay. See «FUEL PUMP RELAY LOCATIONS»(ref-134958-S24753694332002022100000) table. Connect fused jumper wire between ground and fuel pump relay socket terminal No. 30. see scheme 3 Reconnect negative battery cable, to operate fuel pump. Observe fuel line pressure. See «FUEL LINE PRESSURE»(ref-134958-S10088893632002022100000) table.
4. If fuel line pressure is high, check for plugged return line. If no problem is found, replace fuel pressure regulator. If fuel line pressure is low, check fuel pump maximum pressure. See «FUEL PUMP MAXIMUM PRESSURE INSPECTION»(ref-134958-S39552896752002022100000). If fuel pump maximum pressure is as specified, check for plugged or restricted fuel line or fuel filter. Repair as necessary. If no problems are found, replace pressure regulator.

FUEL LINE PRESSURE

Fuel Pump Inspection

1. Fuel pump is located inside fuel tank. Locate DLC-1 on left side of engine compartment. Connect a fused jumper wire between DLC-1 terminals F/P and GND. On 626, remove fuel pump relay and ground relay socket terminal No. 30. see scheme 2or see scheme 3. Remove fuel filler cap. Turn ignition switch on. Listen for fuel pump operation at fuel filler pipe. Install fuel filler cap.
2. If fuel pump does not operate, Disconnect fuel pump connector. Using DVOM, check for continuity between fuel pump connector terminals "B" and "D" (terminals "A" and "D" on 626). If continuity is not present, replace fuel pump. If continuity is present, check for open or short circuit in wiring harness between fuel pump and fuel pump relay. See «WIRING DIAGRAMS»(ref-134975) article.

Fuel Pump Hold Pressure Inspection

1. Disconnect negative battery cable. Release fuel pressure. See «FUEL PRESSURE RELEASE»(ref-134958-S02405930982002022100000). Disconnect fuel inlet hose at fuel rail. Install fuel pressure gauge to fuel inlet hose and plug fuel pressure gauge outlet hose. On 626, go to next step. On all other models, go to step 3.
2. Locate and remove fuel pump relay. Ground fuel pump relay socket terminal No. 30. Reconnect negative battery cable for 10 seconds to operate fuel pump. Disconnect negative battery cable and jumper wire. Wait 5 minutes and observe fuel pressure. See «FUEL PUMP HOLD PRESSURE»(ref-134958-S26752390982002022100000) table. If fuel pressure is not as specified, replace fuel pump.
3. Reconnect negative battery cable. Locate DLC-1 on left side of engine compartment. Connect a fused jumper wire between DLC-1 terminals F/P and GND. see scheme 2 Turn ignition switch on for 10 seconds to operate fuel pump. Turn ignition switch off and disconnect fused jumper wire. Wait 5 minutes and observe fuel pressure. See «FUEL PUMP HOLD PRESSURE»(ref-134958-S26752390982002022100000) table. On all models, if fuel pressure is not as specified, replace fuel pump.

FUEL PUMP HOLD PRESSURE

Fuel Pump Maximum Pressure Inspection

1. Disconnect negative battery cable. Release fuel pressure. See «FUEL PRESSURE RELEASE»(ref-134958-S02405930982002022100000). Disconnect fuel inlet hose at fuel rail. Install fuel pressure gauge to fuel inlet hose and plug fuel pressure gauge outlet hose. On 626, go to next step. On all other models go to step 3.
2. Locate and remove fuel pump relay. Ground fuel pump relay socket terminal No. 30. Reconnect negative battery cable to operate fuel pump. Observe fuel pressure. See «FUEL PUMP MAXIMUM PRESSURE»(ref-134958-S37064208522002022100000) table. Disconnect negative battery cable and jumper wire. If fuel pressure is not as specified, replace fuel pump.
3. Locate DLC-1 connector in left side of engine compartment. Connect a fused jumper wire between data link connector terminals F/P and GND. see scheme 2 Turn ignition switch on to operate fuel pump and observe fuel pressure. See «FUEL PUMP MAXIMUM PRESSURE»(ref-134958-S37064208522002022100000) table. Turn ignition switch off and disconnect fused jumper wire. If fuel pressure is not as specified, replace fuel pump.

FUEL PUMP MAXIMUM PRESSURE

Fuel Pump Relay Inspection (Miata)

Note. The fuel pump relay housing is easily broken when relay is removed. Test relay in place and remove relay only for replacement.

Disconnect negative battery cable. Disconnect fuel pump relay 6-pin harness connector. FUEL PUMP RELAY LOCATIONS table. Check continuity between fuel pump relay terminals "A" and "B" and terminals "C" and "E". (Scheme 2) Continuity should be present between fuel pump relay terminals "A" and "B" and not between terminals "C" and "E". Using fused jumper wires, connect positive battery terminal to fuel pump relay terminal "A". Connect negative battery terminal to fuel pump relay terminal "B". Continuity should be present between fuel pump relay terminals "C" and "E". Replace relay if continuity is not as specified.

Scheme 2

Fuel Pump Relay Inspection (Millenia 2.5L, Protege, Protege5 & 626)

Remove fuel pump relay. See FUEL PUMP RELAY LOCATIONS table. Using ohmmeter, check for continuity between relay terminals "C" and "D" (terminals "B" and "E" on 626). (Scheme 3)and (Scheme 4). Continuity should not be present. Using fused jumper wires, connect positive battery terminal to fuel pump relay terminal "A". Connect negative battery terminal to fuel pump relay terminal "B" (terminal "F" on 626). Continuity should be present between fuel pump relay terminals "C" and "D" (terminals "B" and "E" on 626). If continuity is not as specified, replace fuel pump relay.

Scheme 3

Scheme 4

Fuel Pump Relay Inspection (MPV)

Remove fuel pump relay. See FUEL PUMP RELAY LOCATIONS table. Using ohmmeter, check for continuity between relay terminals "C" and "D". (Scheme 5) Continuity should not be present. Using fused jumper wires apply battery voltage to terminal "A" and ground terminal "E". Continuity should be present between fuel pump relay terminals "C" and "D" with battery voltage applied. If continuity is not as specified, replace fuel pump relay.

Scheme 5

Fuel Pressure Regulator Inspection

1. Disconnect negative battery cable. Release fuel pressure. See «FUEL PRESSURE RELEASE»(ref-134958-S02405930982002022100000) . Install fuel pressure gauge in fuel supply line. Reconnect negative battery cable.
2. Start and operate engine at idle. Ensure vacuum is available to pressure regulator. Observe fuel pressure with vacuum hose connected and disconnected at fuel pressure regulator. See «REGULATED FUEL PRESSURE»(ref-134958-S03268848942002022100000) table. If fuel pressure is not as specified, replace fuel pressure regulator.

REGULATED FUEL PRESSURE

Injector Fuel Leakage Inspection

1. Disconnect negative battery cable. Release fuel pressure. See «FUEL PRESSURE RELEASE»(ref-134958-S02405930982002022100000). Using mechanics wire, secure each fuel injector to fuel rail. Disconnect fuel injector connectors. Remove fuel rail assembly from intake manifold. See «FUEL SYSTEM»(ref-134974-S38674965952002022100000) in REMOVAL, OVERHAUL & INSTALLATION article. Reconnect fuel lines to fuel rail. On 626, go to next step. On all other models, reconnect negative battery cable and go to step 3.
2. Disconnect negative battery cable. Remove fuel pump relay. Connect fused jumper wire between ground and fuel pump relay socket terminal No. 30. Reconnect battery ground cable to operate fuel pump. Tilt injectors about 60 degrees and check injector nozzles for fuel leaks. Fuel leakage should be less than one drop every 2 minutes. If fuel leakage is present, replace injector.
3. Locate DLC-1 on left side of engine compartment. Connect a fused jumper wire between DLC-1 terminals F/P and GND. see scheme 2 Turn ignition switch on. Tilt injectors about 60 degrees and check injector nozzles for fuel leaks. Fuel leakage should be less than one drop every 2 minutes. If fuel leakage is present, replace injector.

Fuel Pressure Inspection

Note. Fuel pump will only operate for about 8 seconds when Output Test Mode is selected and activated.

1. Release fuel pressure. See «FUEL PRESSURE RELEASE»(ref-134958-S02405930982002022100000) . Install fuel pressure gauge. Turn ignition switch on. Connect scan tool to DLC. Select PCM, active command modes, output test mode and fuel pump PID. Press MODE to change to ALL ON mode. Press START, to run fuel pump. Compare fuel pressure reading on fuel pressure gauge with specifications in «FUEL PRESSURE SPECIFICATIONS»(ref-134958-S07707903082002022100000) table.
2. If fuel pressure is to high, replace fuel pump. If fuel pressure is to low, on Tribute, go to next step. On B2300, B3000 and B4000, go to step 4 .
3. Start engine and let run for 10 seconds. Turn ignition switch off. Restart engine and let run for 10 seconds. Turn ignition switch off. Remove vacuum hose from pressure regulator or damper and check for fuel in hose or pulse damper. If fuel is not present, go to next step. If fuel is present, replace fuel pulse damper.
4. Release fuel system pressure and check for restriction in fuel supply line (blockage, kinked or pinched). Using regulated air pressure of 3-5 psi, blow air through fuel supply line. If air flows freely, replace fuel pump. If air does not flow freely, repair restriction as necessary.

FUEL PRESSURE SPECIFICATIONS

Fuel Pressure Hold Inspection

Note. Fuel pump will only operate for about 8 seconds when Output Test Mode is selected and activated.

Release fuel pressure. See FUEL PRESSURE RELEASE . Install fuel pressure gauge. Turn ignition switch on. Connect scan tool to DLC. Select PCM, active command modes, output test mode and fuel pump PID. Press MODE to change to ALL ON mode. Press START, to run fuel pump. Turn fuel pump relay off and observe fuel pressure. Wait one minute. If fuel pressure reading is within 5 psi of previous pressure reading, fuel system is okay. If fuel pressure drops more than 5 psi, inspect fuel injectors for leaks. See Injector Fuel Leakage Inspection .

1. Release fuel pressure. See «FUEL PRESSURE RELEASE»(ref-134958-S02405930982002022100000) . Connect fuel pressure gauge to fuel inlet line at fuel rail. Start engine and run at idle. Record fuel pressure. Disconnect and plug vacuum line at fuel pressure regulator. Drive vehicle under heavy acceleration while monitoring fuel pressure. If fuel pressure holds steady within 3 psi of recorded fuel pressure, go to next step. If fuel pressure did not hold steady, check Fuel Vapor Vent (FVV) valve. See «SYSTEM TESTS (EVAPORATIVE EMISSION)»(ref-134970-S09458215942002022100000) in SYSTEM AND COMPONENT TESTING article. If valve is okay, check for clogged fuel filter. Repair as necessary.
2. Connect vacuum pump to fuel pressure regulator and apply vacuum. If fuel pressure decreases, check for leaking vacuum hose. If fuel pressure does not decrease, replace fuel pressure regulator. Go to next step.
3. Disconnect fuel return line from fuel rail. Connect a short hose from fuel rail to a one liter measuring container. Turn ignition switch on. Engine off. Connect scan tool to DLC. Select PCM, Active Command Modes and OUTPUT TEST MODE. Press MODE to change to ALL ON mode. Press START, to run fuel pump. Measure fuel line pressure and ensure fuel is flowing into container. If fuel pressure or volume is high, replace fuel pressure regulator. If fuel pressure or volume is not high, check return line for blockage or clog. Repair as necessary. Go to next step.
4. Start engine and let run for 10 seconds. Turn ignition switch off. Restart engine and let run for 10 seconds. Turn ignition switch off. Remove vacuum hose from pressure regulator and check for fuel in hose or pressure regulator. If fuel is present, replace fuel pressure regulator.

Scheme 6

Scheme 7

1. Turn ignition switch on. Engine off. Connect scan tool to DLC. Select PCM, Active Command Modes and OUTPUT TEST MODE. Press MODE to change to ALL ON mode. Press START, to run fuel pump. Listen for operation of fuel pump. If fuel pump operation is heard, go to «Fuel Pressure Inspection»(ref-134958-S07639704332002082600000). If pump operation is not heard, go to next step.
2. Disconnect fuel tank assembly 4-pin harness connector. (Scheme 6)or (Scheme 7). Using DVOM check for continuity between fuel tank assembly 4-pin harness connector terminals No. 2 (Pink/Black wire) and No. 4 (Black wire). If continuity is present, go to next step. If continuity is not present, replace fuel pump.
3. With scan tool still connected, Select PCM, Active Command Modes and OUTPUT TEST MODE. Press MODE to change to ALL ON mode. Press START, to run fuel pump. Measure voltage at fuel tank assembly 4-pin harness connector terminal No. 2 (Pink/Black wire). If voltage reading is more than 10.5 volts, go to next step. If voltage reading is 10.5 volts or less, check fuel pump relay or inertia fuel pump shutoff switch.
4. Measure resistance between ground and fuel tank assembly 4-pin harness connector terminal No. 4 (Black wire). If resistance is less than 1 ohm, recheck fuel pump. If resistance reading is 1 ohm or more, repair open circuit on Black wire between ground and fuel tank assembly 4-pin connector terminal No. 4.

Note. Do not reuse fuel injector "O" rings. Replace with NEW "O" rings.

Release fuel pressure. See FUEL PRESSURE RELEASE . Remove fuel rail assembly. Reconnect fuel lines to fuel rails. Disconnect inertia fuel shutoff switch 3-pin harness connector. Install fused jumper wire between battery positive and inertia fuel shutoff switch terminal No. 2 (Pink/Black wire) to run fuel pump. Check for leaks at fuel injectors. If fuel leakage is more than one drop per 2 minutes, remove leaking injector and check for faulty "O" rings or damaged fuel rail. If o-rings and fuel rail are okay, replace fuel injector. Repair as necessary.