If your engine stalls when idling and your jeep has fuel injection, you either have a bad idle air bypass valve, a bad cold start valve, or a faulty fuel pressure regulator.
Let’s take a look at these possibilities by asking a few questions.
Does the engine stay running when you step lightly on the gas pedal?
If your engine does stay running, then a bad idle air bypass valve most likely causes your problem.
The idle air bypass valve is responsible for maintaining your engine’s idle speed, and when you lightly step on the gas, this would override the idle air bypass valve and keep the engine running.
If your engine does not stay running when lightly stepping on the gas, we can rule out the idle air bypass valve and move on to the next question.
Does the vehicle only stall when the engine is cold?
If the engine stalls when it is cold, you have a problem with your cold start valve.
The cold start valve keeps the engine running in fuel injection engines by giving it a little more gas until the vehicle warms up.
We can rule out the cold start valve if the engine stalls when idling, even after it warms up. This would leave only one other possibility, a bad fuel pressure regulator.
Vehicles with fuel injection use a fuel pressure regulator to maintain even pressure to each engine’s fuel injectors. If the fuel pressure regulator is not working properly, your engine will not receive the right amount of fuel and cause your engine stalling.