Technical Car Experts Answers everything you need: Engine will not start when its hot?

Mercury sable will not start when engine is hot or outside temperature is hot.But will start when temp is cold and engine is normal.

When this problem occurs.Check engine light comes on dash and remains steady.If in your case, check engine light is coming ON and remaining steady.Then directly get your mercury scanned at diagnostic center.In scanning you will get error codes.The error code will point out what is causing this problem.

BUT,if in your case the check engine light is not coming ON,then in that case the problem is bad crankshaft sensor.When crank shaft sensor goes weak, it will stop functioning when it gets hot.But when engine gets cold the sensor starts functioning and engine computer gets proper signal.
So the crank shaft sensor needs to be tested and replaced.

Below is the testing and dis-assembly directions with diagram for mercury sable.

Ford Taurus/Sable 1996-1999

Crankshaft Position Sensor

OPERATION.
TESTING.
REMOVAL & INSTALLATION.
OPERATION

The Crankshaft Position (CKP) sensor is a variable reluctance sensor that uses a trigger wheel to induce voltage. The CKP sensor is a fixed magnetic sensor mounted to the engine block and monitors the trigger or pulse wheel which is attached to the crank pulley/damper. As the pulse wheel rotates by the CKP sensor, teeth on the pulse wheel induce voltage inside the sensor through magnetism. The pulse wheel has a missing tooth that changes the reading of the sensor. This is used for the Cylinder Identification (CID) function to properly monitor and adjust engine timing by locating the number 1 cylinder. The voltage created by the CKP sensor is alternating current (A/C). This voltage reading is sent to the PCM and is used to determine engine RPM, engine timing, and is used to fire the ignition coils.

TESTING

See Figure 1

Fig. Fig. 1: Test the CKP sensor for output voltage while the engine is cranked or running. Voltage should be more than 0.1 volts A/C

Measure the voltage between the sensor CKP sensor terminals by backprobing the sensor connector.

If the connector cannot be backprobed, fabricate or purchase a test harness.
Sensor voltage should be more than 0.1 volt AC with the engine running and should vary with engine RPM.
If voltage is not within specification, the sensor may be faulty.

REMOVAL & INSTALLATION

See Figures 2 through 6

: Fig. 2: CKP sensor mounting-3.0L OHV (2 valve) engine

: Fig. 3: CKP sensor mounting-3.0L OHC (4 valve) engine

FIG : Fig. 4: CKP sensor mounting-3.4L (SHO) engine

Fig. Fig. 5: Remove the two CKP sensor retaining screws and...

Fig. Fig. 6: ... remove the CKP sensor from the engine

Disconnect the negative battery cable.
Raise and safely support the vehicle.
Remove the passenger side inner fender splash shield.
Detach the electrical connector for the CKP sensor.
Remove the CKP sensor retaining bolts and remove the CKP sensor.
The installation is the reverse of removal.

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