Owner's Problem Description
The owner reports that the vehicle cut off while approaching a stop sign and would not restart. Dashboard lights indicate power is present, and the alternator has been tested and confirmed operational. Two weeks prior, the vehicle also cut off but restarted with the battery indicator light illuminated. The owner suspects the starter might be the cause of the issue. The vehicle is currently unable to restart.
Professional Technical Analysis
The 1995 Mitsubishi Galant, equipped with a typical 2.0L 4-cylinder engine and approximately 150,000 miles, is exhibiting symptoms of intermittent stalling and failure to restart. The vehicle cut off while decelerating at a stop sign, indicating a potential electrical or fuel delivery issue. Despite dashboard lights indicating power, the starter's engagement during cranking seems jerky, possibly due to a failing overrunning clutch. There is a history of the vehicle cutting off previously, which suggests a pattern that could be related to the ignition system or fuel supply. The alternator has been tested and confirmed to provide proper voltage output (13.8-14.4V) under load, ruling out charging issues. This situation raises concerns regarding the starter's functionality; a faulty starter can lead to poor engagement and may intermittently disengage while driving, leading to stalling. Furthermore, checking for any stored DTCs (Diagnostic Trouble Codes) is vital as they could provide insight into potential issues with the crankshaft position sensor or ignition control module, both of which can affect engine performance. The current condition of the vehicle is concerning, as it poses safety risks if it stalls in traffic. Therefore, accurate diagnostics are essential to determine the root cause of these symptoms.
Possible Causes
Most common causes (ordered by frequency):
- Starter Motor Failure: The starter motor may be exhibiting symptoms of a failing overrunning clutch, resulting in a jerky cranking motion. This could prevent the engine from starting properly, especially if the starter is not fully engaging due to internal wear or electrical issues. Typically, a starter motor should draw around 12V during engagement and produce a smooth cranking speed. Testing the starter's current draw and verifying the solenoid operation can help confirm this issue. - Intermittent cranking issues, jerky motion during cranking, potential grinding noise indicating starter engagement problems.
- Ignition System Malfunction: An issue with the ignition control module or a failing crankshaft position sensor can lead to intermittent loss of spark, causing the engine to stall unexpectedly. If the vehicle experiences a no-start condition when hot, this could suggest thermal failure of the ignition components. Testing the ignition coil and associated wiring for proper resistance values (typically 0.5-2 ohms for coils) is necessary to rule out this possibility. - Check engine light activation, intermittent stalling, potential P0335/P0340 codes indicating crankshaft position sensor issues.
- Fuel Delivery Issue: A failing fuel pump or clogged fuel filter could result in insufficient fuel pressure, preventing the engine from starting. The fuel pump should maintain a pressure of 35-45 PSI. If the pressure drops below this threshold, it may indicate a problem with the fuel pump relay or the fuel pump itself. Conducting a fuel pressure test can confirm this. - Low fuel pressure readings, engine sputtering during acceleration, fuel pump relay clicking sound.
Diagnostic Steps
Professional Diagnosis Process
Follow these systematic steps to accurately diagnose the issue. Each step builds on the previous one to ensure accurate diagnosis.
- STEP 1 - Initial OBD-II Scan: Use a professional OBD-II scanner or the GeekOBD APP to retrieve any stored trouble codes. This can help identify issues related to the ignition system, fuel system, or other related components. Pay attention to any codes that may indicate sensor failures or communication errors.
- STEP 2 - Fuel Pressure Test: Attach a fuel pressure gauge to the service port on the fuel rail. Verify that the fuel pressure is within the expected range of 35-45 PSI during key-on and cranking conditions. If the pressure is below this range, further investigate the fuel pump and filter for clogs or failures.
- STEP 3 - Starter Voltage Test: Test the starter motor by measuring the voltage at the starter solenoid while cranking. A healthy starter should receive around 12-14V during cranking. If voltage is inadequate, check the battery and cables for corrosion or loose connections.
- STEP 4 - Ignition System Check: Inspect the ignition coil and associated wiring for signs of wear or failure. Measure the resistance of the ignition coil to ensure it falls within the typical range of 0.5-2 ohms. If the resistance is out of specification, replacement may be necessary.
