The '99 4x4 I gave to my son in law w/ less than 100k miles is having issues. Will start good, but starts to stumble & then dies within a few minutes. Stock truck with no modifications. The plenum gasket was changed once. Any clues on where to look?
thanks
Mike Sal

 

Mike Sal, try tapping on the bottom of your fuel tank near where the fuel pump is with a rubber mallet or something while someone is starting it. This happened to me about a year ago. Always keep safety in mind and trust who is in the drivers seat. Sounds like your fuel pump is going. Good luck!

 

Might be the CPS on the back, up by the passenger side bell housing. No way to really check it if it's bad. If you do decide to replace it, get a MOPAR one. AZ, PEP boys, Napa and Oreileys CPS are a POS.

 

I would start at cleaning the idle air control valve and go from there. A fuel pressure check would be good to know if possible.

 

Looked at truck today. Starts right up but starts to stumble quickly. If u give it some gas to get rpms up it sounds smoother. Didn’t put it in gear. Picked up some plugs n a o2 sensor but didn’t have any tools. How do you read the codes on a 99?

 

I use a code reader that I got from the auto parts store.

 

It's still in open loop if it stumbles right away when cold and isn't using the O2 sensor yet. Sounds more like a IAC valve or TPS. I'd try a IAC from Mopar or Standard Motor Products and clean the well inside the throttle body.

 

Or low fuel pressure.

 

If fuel pressure were a contributor, wouldn't the stumble get worse with increase of rpm's?

 

Depends on how low it is..... computer can compensate to some extent, but, at idle, it is mostly running off tables. For X temp, Y throttle position, and Z airflow, it injects W microseconds of fuel.

Wouldn't hurt to check it.

What spark plugs do you have in it? Rare earth plugs can present these issues as well.