Need Help! 99 XJ Not Running

[mack]

Son has a 99 XJ, it won't stay running when you take your foot off gas. We cleaned the idle air control valve off but it still dies. Any suggestions?

 

[zubz]

Does it have fuel pressure?
Have you checked the the normal stuff yet?

 

[mack]

I was thinking fuel pump but I can not tell or hear if it's making a noise.

 

[Fabrik8]

Check throttle position sensor. Does it run fine other than that? If it does, I have a hard time believing it's a fuel system problem. Having a fuel system problem when the fuel demand is at its absolute lowest would be very rare.

Any difference when the engine is cold versus when warmed up? If there's a difference, it could be a fast idle thermo valve (if that engine has one) or coolant temp sensor (for the ECU, not the gauge sender). I'm not very knowledgeable about 90s Jeeps, just fuel injected engines in general.

 

[mack]

I friend told me to replace the idle air control valve, fuel pressure was good. $70 latter it starts up and runs fine now. I had no idea what that part was.

 

[Fabrik8]

Can't keep the throttle plate opened slightly for idle airflow because that opening amount would change every time the weather or temperature changed. Gotta have something to dynamically control airflow around the throttle plate because you don't have a drive-by-wire throttle to do it. That's what that part does.

 

[mack]

Ahh..I see, I was thinking fuel pump until I checked pressure. I wish I was a mechanic. ..lol

 

[Mac5005]

Ahh..I see, I was thinking fuel pump until I checked pressure. I wish I was a mechanic. ..lol

What was the pressure?