* Fuel filter: A clogged fuel filter can restrict fuel flow, especially under stress. Even with a new pump, insufficient fuel can reach the engine, leading to stalling.
* Ignition system: Problems with the ignition coil, distributor (if applicable), spark plugs, wires, or crankshaft position sensor can cause misfires and stalling, particularly under load.
* Mass airflow sensor (MAF): A faulty MAF sensor provides inaccurate air/fuel mixture readings to the engine computer, leading to improper fuel delivery and stalling.
* Throttle position sensor (TPS): A malfunctioning TPS provides incorrect throttle position information, causing the engine to run lean or rich, resulting in stalling.
* Vacuum leaks: Leaks in the vacuum system can disrupt the engine's operation, leading to stalling.
* Transmission issues: In an automatic transmission, problems like low fluid, worn clutch packs, or a failing torque converter can cause stalling under load (such as going uphill).
* Fuel pressure regulator: This regulates fuel pressure in the fuel rail. A faulty regulator might deliver insufficient pressure even with a new pump.
* Computer problems (PCM/ECM): The Powertrain Control Module (PCM) or Engine Control Module (ECM) could be faulty, causing improper fuel delivery or other issues.
To diagnose the stalling problem, a mechanic needs to systematically check these components. Simply replacing the fuel pump is only addressing one potential cause. The fact that it still stalls suggests the problem lies elsewhere. A proper diagnostic scan using an OBD-II scanner would be a good starting point.
