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Q: Car will not stay running when I take my foot off the gas pedal.

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Car doesn't start unless I step on accelarator,shuts off when I take it off ! Will that be carburetor or Gas pump

My car has 231689 miles.
My car has an automatic transmission.

A: The fuel injection system does nothing unti...

The fuel injection system does nothing until the engine is turning (starting or running), so pressing the pedal before you start will make no difference. The fuel injectors work at any RPM, so a choke is not necessary. The computer simply feeds a little extra gas through the fuel injectors to start the engine. On the old carburetor engines, you pressed the gas pedal before starting to set the choke position and give a squirt of fuel into the engine via the accelerator pump. This was necessary because the carburetor does not feed fuel as efficiently as a fuel injection system does at low (starting) RPM.

It may be likely that you have a faulty idle air control valve. The idle air control valve reads the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at idle. Since this valve is controlled by the vehicle’s computer, it will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. When you accelerate, the engine RPM increases, and as you let off the gas, the RPM slowly returns to the normal idling speed with the help of the idle air control valve. When the engine RPM drops below the normal range of about ~800 RPM, this often times will cause the engine to stall indicating a dirty or faulty idle air control valve. I would recommend having an expert from YourMechanic come to your location to diagnose and repair your idle air control valve.

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