fuel pump MAZDA MX-5 1994 Owner's Manual

F TROUBLESHOOTING GUIDE INSPECTION :heck for correct intake manifold vacuum at idle Vacuum: More than 450 mmHg I17.7 inHg) VACUUM GAUGE :heck if PCME terminal voltages are OK (2D, 20 and 2Q) page F-146 :heck for correct ignition timing at idle @S page F-76 Ignition timing: 10" + 1" BTDC :heck for correct fuel line pressure at idle @S page F-11 0 Fuel line pressure: 265--314 kPa f2.7-3.2 kgf/cm2,38-46 psi} (Vacuum hose to pressure regulator discon- INSTALL CLAPS ' :heck if strong blue spark is visible at each discon- iected high-tension lead while cranking engine - -- :heck for correct engine compression @S Section B Engine compression: 1,255-883 kPa (12.8-9.0 kgf/cm2, 182-128 psi)-300 rpm - Yes Yes Yes No - Yes - No - Yes No - Yes - No - ACTION Go to next step Low vacuum Check for air leakage of intake air system components page F-100 Go to next step Check for cause (Refer to "Check Point for Each Termi- nal") page F148 Check for correct idle speed page F77 Idle speed: 850 -c 50 rpm (Mi) 800 + 50 rpm (AT) e If OK, go to next step o If not OK, adjust idle speed page F-77 Adjust page F-76 Go to next step Low pressure Check fuel line pressure while pinching fuel return hose 0 If fuel line pressure quickly increases, check pressure regulator page F-118 0 If fuel line pressure gradually increases, check for clog- ging between fuel pump and pressure regulator If not clogged, check fuel pump maximum pressure page F-115 Go to next step Check ignition system (Refer to Troubleshooting "Misfire") Section G Go to next step Check engine condition Section B Worn piston, piston rings or cylinder wall Defective cylinder head gasket Distorted cylinder head Improper valve seating Valve sticking in guide Gartner Banana

TROUBLESHOOTING GUIDE STEP 11 - 12 -- INSPECTION Sonnect data link connector terminals F/P and 3ND with jumper wire and check for correct fuel ine pressure with ignition switch ON page FllO Fuel line pressure: 265-314 kPa (2.7-3.2 kgflcm2, 38-46 psi) - Yes GND FIP INSTALL CLAPS ' I Try known good PCME and check if condition im- proves Daae F-144 ACTION GO to next step Low pressure Check fuel line pressure while pinching fuel return hose 0 If fuel line pressure quickly increases, check pressure regulator page F-118 Q If fuel line pressure gradually increases, check for clog- ging between fuel pump and pressure regulator If not clogged, check fuel pump maximum pressure page F-115 Gartner Banana

TROUBLESHOOTING GUIDE INSPECTION ACTION ;heck if PCME terminal voltages are OK 2M, 20 and 20) usf page F-146 Yes - No Go to next step Check for cause (Refer to "Check Point for Each Terrni- nal") G+F page F-139 >heck if throttle linkage is correctly installed and )perates freely Yes Go to next step Correct, clean, or replace as required any binding or dam- aged linkage and adjust cable deflection at throttle body * page F-101 No - Yes >heck for correct intake manifold vacuum at idle lacuum: More than 450 mmHg (17.7 inHg} VACUUM GAUGE / - - Go to next step Check for air leakage of intake air system components G+F page F-110 >heck if air cleaner element is clean page F-76 Yes Go to next step Replace air cleaner element * page F-99 >heck for correct ignition timing at idle usf page F-76 Yes Check if ignition timing advances when accelerating 0 If advances, go to next step e If no advance, replace PCME page F-143 gnition timing: 10" 2 lo BTDC No - Yes Adjust usf page F-76 >heck for correct fuel line pressure at idle page F-110 Check if fuel line pressure decreases when accelerating quickly %el line pressure: 265-314 kPa {2.7-3.2 kgf/cm2, 38-46 psi) (Vacuum hose to pressure regulator discon- nected) If decreases, check fuel pump maximum pressure page F-115 o If OK, check fuel line and filter for clogging Low pressure Check fuel line pressure while pinching fuel return hose 9 If fuel line pressure quickly increases, check pressure regulator * page F-118 0 If fuel line pressure gradually increases, check for clog- ging between fuel pump and pressure regulator If not clogged, check fuel pump maximum pressure Paae F-115 High pressure Check if fuel return line is clogged INSTALL CLAPS o If OK, replace pressure regulator page F-119 o If not OK, replace Gartner Banana

TROUBLESHOOTING GUIDE ACTION Go to next step INSPECTION :heck if throttle linkage is correctly installed and 3perates freely - Yes - No - Yes - No - Yes - No Correct, clean, or replace as required any binding or dam- aged linkage and adjust cable deflection at throttle body @a page F-103 Go to next step :heck if air duct and air hoses are correctly nstalled page F-99 Repair ~8 page F-99 Go to next step ;heck for correct intake manifold vacuum at idle Vacuum: More than 450 mmHg (17.7 inHg) VACUUM GAUGE Check for air leakage of intake air system components page F-100 :heck if air cleaner element is clean ttzr page F-76 Yes - No Go to next step Replace air cleaner element @a page F-99 >heck for correct ignition timing at idle page F-76 Yes - No Check if ignition timing advances when accelerating Q If advances, go to next step Q If no advance, replace PCME page F-143 Adjust page F-76 gnition timing: 10" a lo BTDC ;heck for correct fuel line pressure at idle page F-110 Yes - No - Yes Check if fuel line pressure decreases when accelerating quickly %el line pressure: 265-314 kPa I2.7-3.2 kgf/cm2, 38-46 psi] (Vacuum hose to pressure regulator discon- a If decreases, check fuel line and filter for clogging 0 If no decrease, go to next step Low pressure Check fuel line pressure while pinching fuel return hose If fuel line pressure quickly increases, check pressure regulator @a page F-118 0 If fuel line pressure gradually increases, check for clog- ging between fuel pump and pressure regulator If not clogged, check fuel pump maximum pressure page F-115 INSTALL CLAPS ;heck for EGR system malfunction page F-124 Repair or replace Go to next step Repair or replace t@~ page F-128 ;heck if exhaust system is restricted page F-128 Yes Go to next step Try known good PCME and check if condition im- )roves page F-144 Gartner Banana

F TROUBLESHOOTING GUIDE INSPECTION ACTION Check if throttle linkage is correctly installed and operates freely Yes Go to next step Correct, clean, or replace as required any binding or dam- aged linkage and adjust cable deflection at throttle body r@ page F-103 Check for correct intake manifold vacuum at idle Vacuum: More than 450 mmHg I17.7 inHg) VACUUM GAUGE / Yes Go to next step No - Yes Check for air leakage of intake air system components r@ page F-100 Go to next step Check if air cleaner element is clean page F-76 Replace air cleaner element page F-99 Check for correct ignition timing at idle page F-76 Yes - No Check if ignition timing advances when accelerating .I, If advances, go to next step o If no advance, replace PCME page F-143 Adjust r@ page M6 Ignition timing: 10" -r- lo BTDC Check for correct fuel line pressure at idle page F-110 Yes Check if fuel line pressure decreases when accelerating quickly Fuel line pressure: 265-314 kPa (2.7-3.2 kgf/cm2, 38-46 psi) (Vacuum hose to pressure regulator discon- nected) o If decreases, check fuel line and filter for clogging 0 If no decrease, go to next step No - Yes Low pressure Check fuel line pressure while pinching fuel return hose 0 If fuel line pressure quickly increases, check pressure regulator page F-113 0 If fuel line pressure gradually increases, check for clog- ging between fuel pump and pressure regulator If not clogged, check fuel pump maximum pressure page F-115 INSTALL CLAPS Repair or replace Check for EGR system malfunction page F-124 No - Yes - No Go to next step - -- Check if exhaust system is restricted page F-128 -- - Repair or replace So to next step Try known good PCME and check if condition im- 3roves page F-144 Gartner Banana

TROUBLESHOOTING GUIDE INSPECTION ACTION :heck for correct intake manifold vacuum at idle Iacuum: More than 450 mmHg i17.7 inHg} VACUUM GAUGE / :heck if air cleaner element is clean page F-76 Check for fuel injector operating sound at idle Check if battery positive voltage exists at fuel injec- tor connector B terminal Check if PCME terminal voltages are OK (1 R, 1 T, 2D, 20 and 2Q) page F-146 Check for correct fuel line pressure at idle page F-110 Fuel line pressure: 265--314 kPa i2.7-3.2 kgf/cm2, 38-46 psi) (Vacuum hose to pressure regulator discon- nected) INSTALL CLAPS Yes - No Yes - No - Yes No - Yes Yes No - Yes - No Go to next step -- - --- Check for air leakage of intake air system components r@= page F-100 Go to next step Replace air cleaner element ~8 page F-99 Go to Step 14 Go to Step 13 check if fuel injector resistance is OK page F-119 Resistance: 12-16R 6 If OK, check wiring between PCME and fuel injector E+Y page F-7 6 If not OK, check fuel injector for fuel leakage page F-120 Check wiring between PCME and fuel injector page F-7 Go to next step Check for cause (Refer to "Check Point for Each Termi- nal") page F-148 Check if fuel line pressure decreases when accelerating quickly c:, If decreases, check fuel pump maximum pressure @r page F-115 If OK, check fuel line and filter for clogging o If no decreases, go to next step Low pressure Check fuel line pressure while pinching fuel return hose ~2 If fuel line pressure quickly increases, check pressure regulator I@= page F-118 o If fuel line pressure gradually increases, check for clog- ging between fuel pump and pressure regulator r@= page F-119 If not clogged, check fuel pump maximum pressure page F-115 Gartner Banana

TROUBLESHOOTING GUIDE INSPECTION Sheck if air cleaner element is clean page F-76 1 :: :heck for EGR system malfunction Yes page F-124 Check for fuel injector operating sound at idle Yes Check if battery positive voltage exists at fuel injec- Yes tor connector B terminal Check if PCME terminal voltages are OK [I B, 1 T, 2D, 20 and 2Q) Check for correct fuel line pressure at idle Yes @T page F-110 Fuel line pressure: 265-314 kPa (2.7--3.2 kgf/cm2, 38--46 psi} (Vacuum hose to pressure regulator discon- nected) i INSTALL CLAPS I ACTION Go to next step Replace air cleaner element G= page F-99 Repair or replace Go to next step Go to Step 15 Go to Step 14 Check if fuel injector resistance is OK ccsf page F-119 Resistance: Approx. 12-16R - 0 If OK, check wiring between PCME and fuel injector a? page F-7 O If not OK, check fuel injector for fuel leakage page F-120 Check wiring between PCME and fuel injector ccsf page F-7 Go to next step Check for cause (Refer to "Check Point for Each Termi- nal") mzf page F-148 Check if fuel line pressure decreases when accelerating quickly O If decreases, check fuel pump maximum pressure page F-115 If OK, check fuel line and filter for clogging O If no decreases, go to next step Low pressure Check fuel line pressure while pinching fuel return hose 13 If fuel line pressure quickly increases, check pressure regulator mzf page F-118 6 If fuel line pressure gradually increases, check for clog- ging between fuel pump and pressure regulator If not clogged, check fuel pump maximum pressure @ page F-115 Gartner Banana

TROUBLESHOOTING GUIDE INSPECTION Check for correct fuel line pressure at idle Section B ACTION Go to next step - Yes High compression Check engine condition Carbon deposits Engine compression: 1,255-883 kPa 112.8-9.0 kgf/cm2, 182-128 psi)-300 rpm Section B Check for correct fuel line pressure at idle page F-110 Yes - No Check if fuel line pressure decreases when accelerating quickly Fuel line pressure: 265-314 kPa (2.7-43.2 kgf/cm2, 38-46 psi) (Vacuum hose to pressure regulator discon- nected) 0 If decreases, check for clogging between fuel pump and pressure regulator 0 If no decrease, go to next step Low pressure Check fuel line pressure while pinching fuel return hose 0 If fuel line pressure quickly increases, check pressure regulator page F-118 0 If fuel line pressure gradually increases, check for clog- ging between fuel pump and pressure regulator If not clogged, check fuel pump maximum pressure w page F-115 INSTALL CLAPS Check for correct ignition timing at idle IJ&T page F-76 Yes Check if ignition timing advances when accelerating o If advances, go to next step o If no advance, replace PCME LW page F-143 Ignition timing: 10" + lo BTDC No - Yes Adjust page F-76 Check for EGR system malfunction page F-124 Repair or replace Go to next step Go to next step Check if cooling system is OK Section E Yes No - Yes Repair or replace Thermostat Electric cooling fan Radiator ~3 Section E Section B Section E Try known good PCME and check if condition im- proves IJ&T page F-144 Replace PCME page F-143 Change fuel to another brand or use higher octane fuel Gartner Banana

INTAKE AIR SYSTEM INTAKE AIR SYSTEM COMPONENTS Removal 1 Inspection l Installation Warning Fuel vapor is hazardous. It can very easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel. Fuel in the fuel system is under high pressure when the engine is not running. Warning Fuel line spills and leaks are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete the follow- ing "Fuel Line Safety Procedures". Fuel Line Safety Procedures A. Release the fuel pressure before disconnecting a fuel line. 1. Start the engine. 2. Remove the fuel pump relay. 3. After the engine stalls, turn the ignition switch to OFF. 4. lnstall the fuel pump relay. B. Avoid leakage. 1. When disconnecting a fuel line hose, wrap a rag around it to protect against fuel leakage. 2. Plug the hose after removal. C. lnstall hose clamps to secure the fuel pressure gauge connections. 1. Drain the engine coolant. (Refer to section E.) 2. Remove in the order shown in the figure. 3. Check the components for damage and repair or replace as necessary. 4. lnstall in the reverse order of removal, using new gaskets. 5. Refill the engine coolant. (Refer to section E.) Gartner Banana

FUEL SYSTEM F FUEL SYSTEM DESCRIPTION . This system supplies the necessary fuel for combustion at a constant pressure to the fuel injectors. Fuel is metered and injected into the intake manifold according to the injection control signals from the power- train control module (engine). The system consists of the fuel tank, the fuel pump, the fuel filters, the fuel distributor, the pressure regulator, the fuel injectors, and the fuel pump relay. I I 1. Fuel tank 5. Fuel pump relay Removal / Inspection / Inspection .................. page F-117 Installation ................ page F-111 Replacement ............... page F-117 2. Fuel filter 6. Pressure regulator Replacement ............... page F-113 Inspection .................. page F-118 3. Fuel pump Replacement ............... page F-119 .................. w Inspection page F-114 7. Fuel injector Replacement ............... page F-115 Inspection .................. page F-119 4. Fuel distributor Removal ................... page F-119 Installation ................. page F-121 Gartner Banana