Owner's Problem Description
The owner replaced the steering column from a salvage yard, after which the car starts but immediately dies after one second. They noticed the plugs were wet with gas, leading them to suspect a fuel delivery issue. The owner charged the battery and added gas, but the problem persists. They considered the crankshaft or camshaft sensor as potential issues but doubted these since the car can start for a moment. An ignition switch from a previous repair is also connected under the dash, raising concerns about its involvement.
Professional Technical Analysis
The 1994 Pontiac Grand Prix is equipped with a 3.1L V6 engine and has an automatic transmission, typically showing around 150,000 miles. The reported issue occurs immediately after the replacement of the steering column from a salvage yard. Symptoms indicate that the vehicle can start but dies within one second. This behavior suggests potential issues related to the ignition or fuel delivery systems. The wet spark plugs indicate excessive fuel delivery, possibly due to a faulty ignition system or incorrect wiring during the column replacement. The connection of the old ignition switch raises further concerns about its compatibility and function with the new column. The engine’s PCM may not be receiving the correct signals to maintain operation, leading to a stall condition. The vehicle should be assessed for proper voltage at the ignition switch and correct wiring to components like the fuel pump and crankshaft position sensor. Safety concerns arise from the possibility of flooding the engine, which could lead to further complications if not addressed. Overall, the combination of a new column and potential miswired components can lead to these intermittent operational issues.
Possible Causes
Most common causes (ordered by frequency):
- Faulty ignition switch connection: If the ignition switch from the previous setup was improperly connected or incompatible with the new steering column, it might not send the correct signal to the PCM to keep the engine running. This miscommunication can lead to the engine starting and then stalling immediately. Proper voltage at the ignition switch should be around 12V when in the 'run' position. If the switch is failing, it may need to be replaced with an OEM part (e.g., P/N 12345678). - Engine starts but stalls immediately, testing reveals inadequate voltage at the ignition switch.
- Fuel system issue: The wet spark plugs indicate that the engine is receiving fuel, but it may not be ignited due to a weak spark or timing issue. Fuel pressure should be tested to ensure it is within the normal range of 35-45 PSI. If the pressure is too high or low, it could suggest a failing fuel pump or pressure regulator. Fuel injectors should also be checked for proper operation and cleanliness. - Spark plugs are wet with fuel, indicating possible fuel delivery issues. Testing shows fuel pressure out of range.
- Miswired components during column replacement: If any wiring connections during the steering column replacement were incorrect or if components were swapped, this could lead to a failure in the PCM receiving the necessary signals. Checking wiring diagrams and ensuring all connectors are properly seated is crucial. A multimeter can be used to verify continuity and proper voltage at each connection. - Inspection of wiring reveals potential mismatches, and testing shows continuity issues.
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 - OBD-II Scanning: Start by connecting a reliable OBD-II scanner or the GeekOBD APP to retrieve any stored trouble codes. Since the vehicle has been experiencing starting issues, check for any relevant codes that may indicate problems with the ignition or fuel system.
- STEP 2 - Voltage Testing: Use a multimeter to measure voltage at the ignition switch while the key is in the 'run' position. Ensure it reads around 12V. Also, check the voltage at the fuel pump connector to ensure it is receiving power when the ignition is activated. This ensures the fuel system is operational.
- STEP 3 - Fuel Pressure Check: Install a fuel pressure gauge at the fuel rail test port to measure the fuel pressure. It should be within 35-45 PSI. If the pressure is outside this range, inspect the fuel pump and pressure regulator for faults. Also, check the fuel injectors for clogs or malfunctions.
- STEP 4 - Wiring Inspection: Review wiring connections related to the steering column and ignition system. Ensure all connectors are seated properly and check for any damage or corrosion. This may involve tracing wires from the ignition switch to the PCM and fuel pump.
