If your fuel pump is not providing enough pressure, it can cause the engine to stall when you let go of the key. Check the fuel pump pressure with a fuel pressure gauge. If the pressure is low, replace the fuel pump.
Fuel Filter
A clogged fuel filter can also restrict fuel flow and cause the engine to stall. Replace the fuel filter every 15,000 miles or as recommended by your vehicle’s manufacturer.
Vacuum Leak
A vacuum leak can cause the engine to stall because it allows air to enter the engine that is not being metered by the mass airflow sensor. This can cause the engine to run lean and stall. Check for vacuum leaks by inspecting the vacuum hoses and connections. If you find any leaks, repair them immediately.
Idle Air Control Valve
The idle air control valve (IACV) controls the amount of air that bypasses the throttle body at idle. If the IACV is not functioning properly, it can cause the engine to stall. Clean the IACV with a throttle body cleaner and check its operation. If the IACV is not functioning properly, replace it.
Throttle Position Sensor
The throttle position sensor (TPS) tells the engine control module (ECM) how far the throttle is open. If the TPS is not functioning properly, it can cause the engine to stall. Check the TPS with a multimeter and replace it if necessary.
