Engine Controls - Basic Engine Testing - 3.0L: Other Mercury Sable III

Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions. Compression pressures are considered within specification if the lowest reading cylinder is within 75 percent of the highest reading cylinder.

Exhaust System Backpressure

The exhaust system can be checked with a vacuum or pressure gauge. If using a pressure gauge, remove oxygen sensor or air injection check valve (if equipped). Connect a 0-5 psi pressure gauge and run engine at 2500 RPM. If exhaust system backpressure is greater than 2 psi, exhaust system or catalytic converter is plugged.

If using a vacuum gauge, connect vacuum gauge hose to intake manifold vacuum port. Start engine. Observe vacuum gauge. Open throttle part way and hold steady. If vacuum gauge reading slowly drops after stabilizing, check exhaust system for restriction.

PRELIMINARY CHECKS

Ensure following systems and components are in good condition and operating properly before diagnosing problems in fuel injection system.

1. Check battery and charging system condition.
2. Check all wiring and vacuum connections.
3. Check air cleaner and ducting.
4. Check secondary ignition components.
5. Check fuel delivery system.
6. Check fuel tank contents and fuel gauge accuracy.
7. Check for dirt, water or other contamination in fuel.
8. Check fuel lines and fittings for leaks.
9. Check fuel delivery system for proper pressure and volume.
10. Check for inoperative fuel injectors.
11. Check cooling system.
12. Check inertia fuel shutoff switch.
13. Check for hydrostatic lock (liquid in cylinder).
14. Check for improperly installed electronic equipment such as anti-theft system, CB radio, cellular telephone or stereo.

FUEL PRESSURE RELEASE

1. Remove fuel cap to release fuel tank pressure. Remove relief valve service port cap. Relief valve service port is located on fuel supply manifold. Using Fuel Pressure Gauge (T80L-9974-B), release fuel pressure from relief valve (Schrader valve).
2. If fuel pressure gauge is not available, disconnect electrical connector to IFS switch. For IFS switch location, see INERTIA FUEL SHUTOFF (IFS) SWITCH LOCATION table under INERTIA FUEL SHUTOFF (IFS) SWITCH. Crank engine for 15 seconds to reduce system pressure.

FUEL PRESSURE

1. Visually inspect fuel system, including fuel lines, connections, injectors and electrical connections. Ensure Inertia Fuel Shutoff (IFS) switch is not tripped. Check condition of battery and fuses. Ensure fuel level in tank is sufficient.
2. Turn ignition off. Release fuel pressure. Install fuel pressure gauge. Start engine and increase engine speed to 2500 RPM. If engine will not start, cycle ignition switch several times. Measure and record fuel pressure. For fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(ref-123323) article. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, go to appropriate circuit test as follows: Go to CIRCUIT TEST HC in TESTS W/CODES article for fuel system diagnosis.
3. With fuel pressure gauge still installed, cycle ignition switch on and off several times. Record fuel pressure. If fuel pressure is at least 25 psi (172 kPa) after one minute with ignition off, system is capable of maintaining fuel pressure. If fuel pressure is not at least 25 psi after one minute with ignition off, check for leaking fuel injectors or fuel pressure regulator.

Fuel Injector Resistance

Disconnect injector harness connectors. Using digital ohmmeter, measure resistance between injector terminals. See INDIVIDUAL INJECTOR RESISTANCE table. Replace any injector not within specification.

Fuel Injector Check

Start engine and allow to idle. If engine will not start, crank engine for 10 seconds. Using a stethoscope, listen for clicking sound at each injector. If clicking sound is heard, fuel injector is operating. If clicking sound is not heard, go to step 8) of CIRCUIT TEST HD in G -TESTS W/CODES article.

INDIVIDUAL INJECTOR RESISTANCE (1)

Note. For additional fuel injector testing, go to step 8) of CIRCUIT TEST HD in TESTS W/CODES article.

INERTIA FUEL SHUTOFF (IFS) SWITCH

1. If IFS switch is tripped, engine cannot be restarted until switch is manually reset. To reset IFS switch, depress switch button. For IFS switch location, see INERTIA FUEL SHUTOFF (IFS) SWITCH LOCATION table.
2. To test IFS switch, turn ignition off. Remove IFS switch. Shake IFS switch to force it into tripped position (switch open). Check continuity between appropriate IFS switch terminals. See WIRING DIAGRAMS article. Continuity should not exist. Reset switch and ensure continuity exists between appropriate terminals.

INERTIA FUEL SHUTOFF (IFS) SWITCH LOCATION

IGNITION CHECKS

Note. To identify ignition system type by application, see ENGINE/VIN ID article.

Note. For circuit identification, see appropriate wiring diagram in WIRING DIAGRAMS article.

Note. If an ignition failure occurs, ignition system may operate with limited ability using Failure Mode Effects Management (FMEM) or Hardware Limited Operation Strategy (HLOS). When this occurs, trouble codes should be present in PCM memory, engine may be hard to start, and timing will not change.

EDIS (DISTRIBUTORLESS)

Note. If vehicle does not start, go to CIRCUIT TEST A in TESTS W/CODES article.

1. Spark Check Perform self diagnostic QUICK TEST to check for ignition-related fault codes, and repair as necessary. See QUICK TEST in G -TESTS W/CODES article. If no fault codes are retrieved, check ignition system wiring harness for damage or loose connectors. See WIRING DIAGRAMS article. Clean or repair connectors as necessary.
2. If wiring and connectors are okay, use Neon Bulb Spark Tester (D8IP-6666-A) to check for spark at each spark plug wire while cranking engine. If spark is strong and consistent at each spark plug (one spark per crankshaft revolution), ignition system is okay. If spark is not present, go to CIRCUIT TEST A in TESTS W/CODES article.

IGNITION COIL RESISTANCE

V6 IGNITION COIL RESISTANCE

IDLE SPEED & IGNITION TIMING

Ensure idle speed and ignition timing are set to specification. For additional procedures, see ADJUSTMENTS article.

IGNITION TIMING

BASE IGNITION TIMING

IDLE SPEED

Engine idle RPM is controlled by PCM and cannot be changed by standard adjustments. On all models, if idle concerns are present, perform QUICK TEST to check for fuel and ignition system related fault codes. See TESTS W/CODES article.

IDLE SPEED SPECIFICATIONS

SUMMARY

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to TESTS W/CODES article. If no fault codes are found in self-diagnostics, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.