Owner's Problem Description
The owner of a 1993 Dodge Stealth reports that the vehicle ran fine for a month after purchase. Now, when turning the key, it clicks and the engine starts but only runs for a few seconds before dying. They have replaced the fuel filter and fuel pump, checked fuel pressure, and changed the main relay sensor, but the issue persists. The owner is seeking assistance to resolve this stalling problem.
Professional Technical Analysis
This 1993 Dodge Stealth, equipped with a 3.0L V6 engine, shows symptoms of intermittent stalling after initially running for a month following purchase. The owner reports a clicking sound when turning the ignition key, followed by the engine starting and then stalling after a few seconds. Notably, fuel pressure is initially at 38 PSI but drops to 25 PSI before the engine dies, suggesting a fuel delivery issue. The owner has already replaced the fuel filter and pump, and verified that the main relay sensor is functioning. The absence of trouble codes in the OBD-II system makes diagnosis challenging, as does the presence of spark during stall conditions. Possible interconnections include the fuel delivery system and the PCM's control over the fuel injectors. A critical analysis of potential causes will focus on fuel pressure regulation, injector pulse width modulation, and electrical connections within the system. The current vehicle condition raises safety concerns due to the unpredictability of stalling, which could occur during driving conditions, leading to potential accidents. Observations indicate that the fuel pressure drop suggests either a failing fuel pump, a clogged fuel line, or an issue with the fuel pressure regulator. The vehicle's mileage and environmental factors should also be considered in assessing wear patterns on critical components.
Possible Causes
Most common causes (ordered by frequency):
- Fuel Pump Failure: Despite replacement, the fuel pump may not be providing adequate pressure due to internal failure or blockage. The pump should deliver 35-45 PSI consistently. Inspect the wiring harness and connections for corrosion or damage, which can lead to voltage drops affecting pump performance. - Initial fuel pressure at 38 PSI drops to 25 PSI quickly, indicating insufficient fuel delivery.
- Fuel Pressure Regulator Malfunction: The regulator may be stuck or leaking, preventing proper pressure maintenance. A properly functioning fuel pressure regulator should maintain pressure at 35-45 PSI. Testing should include checking for vacuum leaks and ensuring the return line is not clogged. - Fuel pressure fluctuates inconsistently, and signs of fuel leakage around the regulator may be present.
- Electrical Connections Issue: Loose or corroded connections in the fuel pump circuit can lead to voltage drops that impair fuel delivery. Ensure all connectors are clean and securely fastened. Additionally, test the fuel pump relay to confirm it is functioning properly. - Clicking sound noted during ignition indicates potential electrical issues, and visual inspection shows signs of corrosion.
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 - Perform OBD-II Scan: Use a professional OBD-II scanner or the GeekOBD APP to verify that no trouble codes are present. Even though no codes are showing, review freeze frame data and monitor live data for any anomalies during the engine's operation.
- STEP 2 - Fuel Pressure Testing: Attach a fuel pressure gauge to the fuel rail and verify fuel pressure at key-on and during engine operation. The pressure should remain above 35 PSI; a drop indicates potential issues with the pump or regulator. Document pressure changes as the engine runs to identify patterns.
- STEP 3 - Inspect Electrical Connections: Visually inspect electrical connectors related to the fuel pump circuit for corrosion or loose connections. Use a multimeter to verify voltage at the fuel pump connector while the engine is cranking and running. Voltage should be around 12V.
- STEP 4 - Relay and Sensor Testing: Test the fuel pump relay and main relay for proper operation. Listen for clicking sounds and check for continuity when activated. If the relay is faulty, replace it with an OEM part. Also, verify the operation of the fuel injectors using the GeekOBD APP to check pulse widths.
