1994 MAZDA MX-5 Workshop Manual

FUEL SYSTEM -- FUEL TANK GAUGE SENDER UNIT SIDE FUEL PUMP 45UOFX-256 1. Remove the rear package trim. 2. Remove the service hole cover. 3. Remove the fuel pump cover. 4. Disconnect the fuel pump connector. 5. Disconnect the fuel hoses. 6. Remove the fuel pump and fuel tank gauge sender unit assembly. 7. Remove the fuel pump. 8. Install in the reverse order of removal, referring to Instal- lation note. Installation note O-ring set 1. Use a new O-ring set. (O-ring, cap, and spacer) 2. Apply oil or fuel to the O-ring set before installing. 3. To confirm sealing of the O-ring, after assembling the fuel pump and fuel tank gauge sender unit, blow air through the fuel main pipe and verify that no air flows. If air flows the check ball may be stuck. Shake the fuel pump 2 or 3 times and recheck. Fuel pump After installing the fuel pump to the bracket, pull down the fuel pump down so that it is tight against the bracket. Gartner Banana

FUEL SYSTEM F FUEL PUMP RELAY Inspection Apply battery positive voltage and a ground to the termi- nals below and check the fuel pump relay operation as described. If not as specified, replace the fuel pump relay. B+: Battery positive voltage Replacement 1. Remove the undercover. B+ A 2. Remove the fuel pump relay. 3. Install in the reverse order of removal. Grounded B Correct result C - E: Continuity Gartner Banana

F FUEL SYSTEM PRESSURE REGULATOR Inspection Fuel line pressure d Warning Fuel line spills and leaks can be dangerous. Fuel can ignite and cause serious injuries or death and can damage the vehicle. Fuel can also irritate skin and eyes. To prevent this from happening, release the fuel pressure according to "Fuel Line Safety Procedures" on page F-108. 1. Disconnect the negative battery terminal. 2. Connect a fuel pressure gauge between the fuel main pipe and the fuel main hose. (Install clamps as shown.) 3. Connect the negative battery terminal. 4. Start the engine and run it at idle. 5. Measure the fuel line pressure. Fuel line pressure: 21 6-264 kPa (2.2-2.7 kgf/cm2, 32-38 psi) Hold pressure Perform this inspection if the fuel pressure hold inspec- tion is not as specified. (Refer to page F-104.) Warning Fuel line spills and leaks can be dangerous. Fuel ,-, can ignite and cause serious injuries or death and can damage the vehicle. Fuel can also irritate skin and eyes. To prevent this from happening, release the fuel pressure according to "Fuel Line Safety Procedures" on page F-108. 1. Disconnect the negative battery terminal. 2. Install a fuel pressure gauge between the fuel pipe and the fuel main hose. (Install clamps as shown.) 3. Connect the negative battery terminal. 4. Connect data link connector terminals F/P and GND with a jumper wire. 5. Turn the ignition switch ON for 10 sec. to operate the fuel pump. 6. Turn the ignition switch OFF and disconnect the jumper wire. 7. Block the outlet of the pressure regulator. 8. Observe the fuel pressure for 5 min. Fuel pressure: More than 147 kPa {I .5 kgf/cm2, 21 psi) 9. If pressure is as specified, replace the pressure regula- tor. Gartner Banana

FUEL SYSTEM F Replacement Warning Fuel line spills and leaks can be dangerous. Fuel can ignite and cause serious injuries or death and can damage the vehicle. Fuel can also irritate skin and eyes. To prevent this from happening, release the fuel pressure according to "Fuel Line Safety Procedures" on page F-108. 1. Disconnect the vacuum hose. 2. Disconnect the fuel return hose. 3. Remove the pressure regulator. Tightening torque: 7.9-10.7 N.m (80-11 0 kgf-cm, 70-95.4 in4bf) 4. Use new O-ring. 5. Install in the reverse order of removal. FUEL INJECTOR Inspection Operation check 1. Warm up the engine and run it at idle. 2. Listen for operational sound of the fuel injector with a screwdriver or a sound scope. 3. If no sound is heard, measure fuel injector resistance. 4. If the fuel injector resistance is OK, check wiring to the fuel injector and powertrain control module (engine) ter- minals 2U, 2V1 2Y and 22 voltages. (Refer to page F-147.) Fuel injector resistance 1. Disconnect the fuel injector harness. 2. Measure resistance of the fuel injector with an ohmme- ter. Resistance: 12-16Q (at 20°C (68°F)) 3. If not as specified, replace the fuel injector. Removal Warning Fuel line spills and leaks can be dangerous. Fuel can ignite and cause serious injuries or death and can damage the vehicle. Fuel can also irritate skin and eyes. To prevent this from happening, release the fuel pressure according to "Fuel Line Safety Procedures" on page F-108. Gartner Banana

FUEL SYSTEM 1. Disconnect the negative battery terminal. 2. Remove the PCV hose. 3. Disconnect the vacuum hose. 4. Disconnect the fuel injector connectors. 5. Remove the fuel distributor and the pressure regulator. 6. Remove the grommets, fuel injectors, and insulators. Inspection Fuel leakage test 1. Firmly affix the fuel injectors to the fuel distributor with wire. 2. Disconnect the fuel injector connectors. 3. Remove the fuel distributor and fuel injectors together with the fuel hoses connected. 4. Connect data link connector terminals FIP and GND with a jumper wire. 5. Turn the ignition switch ON. 6. Tilt the fuel injectors approx. 60 degrees and verify that no fuel leaks from the fuel injector nozzles. 7. If fuel leaks from an fuel injector, replace it. Leakage Specification If there is more than one drop per 2 minutes, replace the fuel injector. d 8. Turn the ignition switch OFF and remove the jumper wire. Gartner Banana

FUEL SYSTEM Volume test Warning Fuel vapor is hazardous. It can very easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel. 1. Remove the air valve. 2. Firmly affix the fuel injectors to the fuel distributor with wire. 3. Disconnect the fuel injector connectors. 4. Remove the fuel distributor and fuel injectors together with the fuel hoses connected. 5. Connect the SST to the battery and an fuel injector. 6. Check the injection volume with a graduated container. Injection volumes: 59-76 ml (59-76 cc, 1.8-2.3 fl oz}/15 sec. 7. If not as specified, replace the fuel injectors. lnstallation Install in the reverse order of removal, referring to Instal- lation note. Tightening torque: Delivery pipe 19-25 N.m (1 .%2.6 kgfm, 14--18 ft4bf) FUEL DISTRIBUTOR MANIFOLD C 45UOFX-282 Installation note 1. Use new injector O-rings. 2. Apply a small amount of clean engine oil to the O-rings before installing. 45UOFX-281 INSULATOR O-RING 3. Use new fuel injector insulators. 4. Install the fuel injectors and new fuel injector insulators. Gartner Banana

PRESSURE REGULATOR CONTROL SYSTEM PRESSURE REGULATOR CONTROL SYSTEM DATA LINK CONNECTOR - CLUTCH SWITCH (MT) (TEN TERMINAL) PARKINEUTRAL SWITCH (PCMT) (AT) THROTTLE POSITION SENSOR L 1 ,,,, INTAKE AIR TEMPERATURE 1 SENSOR (IN MASS AIRFLOW SENSOR) -;- ENGINE COOLANT TEMPERATURE SENSOR PRC SOLENOID VALVE CRANKSHAFT POSITION SENSOR PRESSURE REGULATOR PCME I Above 90°C {194OF} ( Above 70°C {158'F} I Throttle valve closed throttle position or no load condition I Approx. 150 1 I Operating condition Coolant temperature I Intake air temperature I Engine condition I I To prevent percolation of the fuel during hot restart idle, vacuum to the pressure regulator is momentarily cut, and the fuel injection pressure is increased to slightly more than 284 kPa (2.9 kgf/cm2, 41.2 psi}. Operating time (sec) Gartner Banana

PRESSURE REGULATOR CONTROL SYSTEM F PRESSURE REGULATOR / f PRC SOLENOID VALVE AIR FILTER U PRC SOLENOID VALVE lnspection (On-vehicle) 1. Start the engine and run it at idle. 2. Disconnect the vacuum hose from the pressure regula- tor. Verify that vacuum is felt. 3. Ground the PRC solenoid valve terminal B with a jumper wire. Verify that no vacuum is felt. 4. If vacuum exists, check the PRC solenoid valve. Inspection 1. Disconnect the vacuum hose from the PRC solenoid valve and vacuum pipe. 2. Blow through the PRC solenoid valve from port A. 3. Verify that air flows from port B. 4. Disconnect the PRC solenoid valve connector. 5. Connect battery positive voltage and a ground to the ter- minals of the PRC solenoid valve. 6. Blow through the PRC solenoid valve from the port A. 7. Verify that air flows from the valve air filter. 8. If not as specified, replace the PRC solenoid valve. Gartner Banana