Basic Testing - 4-cyl Mazda 323 BF

INTRODUCTION

Note. The following diagnostic steps are here to prevent overlooking a simple problem. This is also the place to start diagnosis for a "NO-START" condition.

The first step in diagnosing any driveability problem is to verify that the problem exists. This may be accomplished by test driving the vehicle under the conditions during which the problem reportedly occurs.

Prior to entering self-diagnostics, a careful and complete inspection of several systems is required. Most driveability or "no start" problems are not related to computerized engine control systems, but are in fact simple mechanical, electrical, fuel or vacuum related faults. Most engine control problems are the result of mechanical breakdowns, poor electrical connections, damaged or misrouted vacuum hoses.

Before considering the computer system as a possible cause of problems, ignition high tension wires, fuel supply, electrical connections and vacuum hoses should be checked. Failure to do so may result in improper diagnosis or lost diagnostic time.

VISUAL INSPECTION

Perform a visual inspection of all electrical wiring. Look for chafed, stretched, cut or pinched wiring. Inspect electrical connectors and connections for tight fit and corrosion. Repair as necessary. Inspect all vacuum hoses for proper routing, cuts or pinches. If necessary, see VACUUM DIAGRAMS section to verify routing and connections. Repair as necessary. Inspect air induction system for possible vacuum leaks, obstructions in air cleaner (ice, mud, etc.) or problems with turbocharger, if equipped.

COMPRESSION

Engine mechanical condition can be checked using a compression gauge, vacuum gauge, or an engine analyzer capable of performing a relative compression test. See engine analyzer instruction manual for availability and description of relative compression feature.

EXHAUST SYSTEM BACKPRESSURE

The exhaust system can be checked with a vacuum gauge or a pressure gauge. Remove O2 sensor or air injection check valve, if equipped. Connect a 1-10 psi gauge and run engine at 2500 RPM. If exhaust system backpressure is over 1 3/4-2 psi, exhaust system or catalytic converter is plugged.

If a vacuum gauge is used, connect it to intake manifold vacuum. Start engine. Observe vacuum gauge. Open throttle part way and hold steady. If vacuum gauge slowly drops after stabilizing, exhaust system should be checked for a restriction.

Fuel Pressure (Electrical)

1. Turn ignition on. Locate fuel control module under left side of dash. Using a jumper wire, connect terminals "B" to "D". Fuel pump (located in tank) should operate. If not, check and replace fuel pump at tank, if necessary. Check fuel pump pressure. See «FUEL PUMP SPECIFICATIONS»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#basic-testing-4-cyl) table. NOTE: Fuel pump controller terminal identification is not available from the manufacturer. FUEL PUMP PERFORMANCE Application Pressure psi (kg/cm 2 ) Min. Vol. in 30 sec. Pts. (L) B2200 Electrical Pump 2.8-3.6 (.20-.25) 1.1 (.53) Mechanical Pump 3.7-4.7 (.26-.33) .9 (.43)
2. If fuel pump operates, remove jumper wire. With ignition on, backprobe rear of fuel pump control unit. There should be 12 volts on terminals "A" and "D" only. If not, check ignition and power feed.
3. Allow engine to idle. There should be 12 volts on terminals "A", "B", "D" and "F" only. If voltage is missing on terminal "B" only, replace fuel pump control unit. If any other terminal did not test as described, check ignition coil (tachometer signal) and power feed.

Fuel Pump (Mechanical)

Test pump for pressure and volume. Replace as necessary.

FUEL INJECTION MODELS

Fuel Pressure

1. On all 4-Cyl moddels, disconnect circuit opening relay (located behind left kick panel on B2600i and 323, on panel near clutch pedal on MX-6 and 626). On MPV, relay is mounted on ECU. ECU is under protective cover on passenger side floor. Start engine (if possible) and allow to die. Connect pressure gauge to fuel line at fuel filter.
2. Turn ignition on. Using a jumper wire, connect terminals of Yellow fuel pump check connector together. Fuel pump check connector is located on firewall, near windshield wiper motor on B2600i, MX-6, 323 and 626, and near airflow sensor on MPV. If pump runs, check fuel pump circuit and circuit opening relay.
3. If possible, start engine. Check fuel pressure with vacuum connected to and disconnected from pressure regulator. Turn engine off and disconnect jumper wire at fuel pump check connector. Wait 10 minutes and ensure residual pressure is at least 21 psi (1.5 kg/cm 2 ).
4. Operate fuel pump by jumpering fuel pump test connector. Check fuel pump performance. Pinch hose between pressure gauge and fuel filter. Do not hold longer than necessary to check pressure. See FUEL PUMP PERFORMANCE table. If pump does not meet specifications, check fuel pump circuits, fuel pump, fuel tank, fuel filter or replace fuel pump.

FUEL PUMP PERFORMANCE

REGULATED FUEL PRESSURE - AT IDLE

Fuel Pump Circuit

1. Turn ignition on. Connect the terminals of Yellow fuel pump check connector with a jumper wire. Fuel pump check connector is located on firewall, under windshield wiper motor on B2600i, 323 and 626, and by airflow sensor on MPV.
2. Listen for fuel pump operating sound. If there is no sound, check main fuse, circuit operating relay, fuel pump and all electrical connections. On all B2600i, MPV, MX-6, 323 and 626 models, airflow meter grounds circuit opening relay and operates fuel pump whenever air flow is present.
3. Circuit opening relay and fuel pump relay on B2600i and MPV are controlled by the computer. For additional testing see TESTS W/CODES and SYSTEM/COMPONENT TESTS articles.

Circuit Opening Relay

1. With relay connected, ensure specified voltage is present at relay terminals. See «FUEL PUMP RELAY CIRCUIT VOLTAGES»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#basic-testing-4-cyl) table. Circuit opening relay on B2600i and 323 is behind the driver's side kick panel. On MPV, relay is mounted on ECU. ECU is under protective cover on passenger side floor. On MX-6 and 626, relay is located on panel near clutch pedal. FUEL PUMP RELAY CIRCUIT VOLTAGES Terminal Ignition "ON" Volts Ignition "OFF" Volts Idle Volts Fp 0 12 12 Fc 12 0 0 B 12 12 12 STA 0 12 0 E1 0 0 0
2. If voltages are okay, remove relay from vehicle. Check relay operation using a 12-volt battery source and making resistance tests. (Scheme 1)

Scheme 1

Transfer Pump (323 4WD Only)

Transfer pump is located in fuel tank. An access panel is located under the rear seat. Transfer pump control unit is located under driver's seat. No testing information is available.

Spark

1. Crank engine. Check for a strong Blue spark at coil wire (if applicable) and at each spark plug wire by using a low voltage spark tester (or holding wire 5/16" from ground). Ensure spark plug wire resistance of each wire is 4880 per foot.
2. Disconnect and inspect all related ignition system connectors and harness. Clean or repair as necessary and recheck SPARK. If still no spark, go to next step.

Ignition Coil Power Source

Disconnect primary wires at ignition coil. Turn ignition on. Using voltmeter, check voltage between coil positive terminal and ground of each ignition coil. Battery voltage should exist. If not, check battery feed, main relay No. 1 (MX-6 and 626 models), ignition switch and fusible links.

Coil Ignitor Power Source (MX-6 Turbo, 626 Turbo)

Disconnect coil ignitor connector. Turn ignition on. Using voltmeter, check voltage between positive terminal (see WIRING DIAGRAMS for wire color) and ground. Battery voltage should exist. If not, check battery feed, main relay No. 1 (MX-6 and 626 models), ignition switch and fusible links.

Ignition Coil Resistance

1. Inspect coil for signs of arcing or leakage. Remove primary and secondary leads from ignition coil. Using ohmmeter, check primary resistance between (positive) and (negative) terminals of coil. (Scheme 2)
2. Check secondary resistance between (positive) terminal and coil tower. See 4-CYL. «IGNITION COIL RESISTANCE»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#basic-testing-4-cyl) table. Replace coil if readings are not within specifications.

Scheme 2

4-CYL. IGNITION COIL RESISTANCE

Pick-Up Coil (B2200, B2600i, MPV, MX-6 Non-Turbo, 323 & 626 Non-Turbo)

1. Disconnect pick-up coil from distributor. Using an ohmmmeter, measure resistance between 2 inner terminals. Replace pick-up coil if resistance is not as specified in «DISTRIBUTOR PICK-UP COIL RESISTANCE»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#basic-testing-4-cyl) table.
2. Ensure ignition coil has battery voltage. If ignition coil resistance and pick-up coil test okay, check for SPARK. If spark is still not available, go to SELF-DIAGNOSTIC TROUBLE CODES.

DISTRIBUTOR PICK-UP COIL RESISTANCE

Crank Angle Sensor (MX-6 Turbo, 626 Turbo)

1. Disconnect crank angle sensor connector from distributor. Measure resistance between terminals indicated in «CRANK ANGLE SENSOR»(/mazda/323/bf-1985-1993/remont/testing-diagnostics/#basic-testing-4-cyl) table. (Scheme 3) If resistance is not as indicated, replace distributor assembly.
2. If ignition coil resistance and crank angle sensor test okay, check for SPARK. If spark is still not available, go to next test.

CRANK ANGLE SENSOR

Scheme 3

Ignitor (MX-6 & 626 Turbo)

1. Turn ignition off. Disconnect ignitor connector and install Test Harness (49 9200 443). Using a needle-type ohmmeter, connect "+" lead to ground and "-" lead to single-pin test wire of test harness. CAUTION: Ensure ohmmeter is installed with "+" lead to ground and "-" lead to single-pin wire of test harness. DO NOT reverse leads, or damage may result.
2. Connect Ignitor Checker (49 F018 002) to other lead of test harness and to battery. (Scheme 4) Set ohmmeter to X1 scale.
3. Turn ignition on. Do not touch ignitor checker "SW1" switch. Push up ignitor checker "SW2" switch and note ohmmeter reading. Ohmmeter needle should jump to 1/2 of the scale and then return. If not, replace ignitor.

Scheme 4

IDLE SPEED & IGNITION TIMING

Ensure idle speed and base ignition timing are set to specification. If necessary, see ON-VEHICLE ADJUSTMENTS.

IDLE SPEED & IGNITION TIMING

SUMMARY

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to TESTS W/CODES . If no codes are present, proceed to TESTS W/O CODES for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.).

See also:
• FUEL PUMP SPECIFICATIONS