Ignition System:
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational position. A faulty CKP prevents proper timing, leading to the engine starting but immediately dying.
* Camshaft Position Sensor (CMP): Similar to the CKP, a bad CMP will disrupt timing and cause the engine to stall.
* Ignition Coil(s): A weak or failing coil may provide insufficient spark to keep the engine running, especially when cold or under load. The Contour has multiple coils (one per cylinder). They could be cracked or failing.
* Ignition Control Module (ICM): This module controls the ignition coils. A faulty ICM can cause intermittent or complete failure of the ignition system.
* Distributor (if equipped): While less likely on a 1995 Contour (depending on engine), if it has a distributor, the cap, rotor, or internal components could be faulty, causing poor spark distribution. The Contour's likely uses coil-on-plug so this is less likely.
* Spark Plugs and Wires: Worn, fouled, or damaged spark plugs or wires can prevent proper combustion.
Fuel Delivery (Beyond the Pump):
* Fuel Pressure Regulator: This regulates fuel pressure in the fuel rail. A faulty regulator might not maintain the correct pressure needed to keep the engine running.
* Fuel Injectors: Clogged or faulty injectors might not deliver the necessary fuel to maintain combustion.
* Mass Airflow Sensor (MAF): This sensor measures the amount of air entering the engine. A faulty MAF sensor provides incorrect information to the computer, leading to improper fuel delivery.
* Throttle Position Sensor (TPS): The TPS tells the computer the throttle's position. A bad TPS can cause erratic fuel delivery and stalling.
Engine Control System:
* Engine Control Module (ECM) / Powertrain Control Module (PCM): The "brain" of the engine. A malfunctioning ECM can cause a wide range of problems, including starting but not staying running. This is usually diagnosed last.
* Wiring Issues: Damaged or corroded wiring harnesses, especially near the engine, can cause intermittent problems.
Troubleshooting Steps:
1. Check for error codes: Use an OBD-II scanner to retrieve any diagnostic trouble codes (DTCs) stored in the ECM. This is the *most important* first step. These codes can pinpoint the problem.
2. Check for spark: Verify you have spark at the spark plugs while cranking.
3. Check fuel pressure: Measure the fuel pressure at the fuel rail.
4. Inspect wiring: Look for any obvious damage or corrosion in the wiring harnesses.
5. Test components: Individually test the sensors listed above using a multimeter or specialized tools.
Without error codes and a check of fuel pressure, diagnosing this issue is difficult. A mechanic with diagnostic equipment will be able to effectively diagnose the problem more efficiently. Ruling out the fuel pump is great, but there are many things in the fuel system itself beyond the pump.
