xj runs for several minutes then dies

93 XJ auto tranny

It was having trouble starting until the old battery ground wires were addressed. It now starts every time but will run 5-15 minutes idling, slowing losing rpms until it dies. It will start right up again after. When put into reverse or drive the rpms will return to normal and idle roughness will calm down.

My possible thoughts would be to check the IAC and possibly the NSS. I've read about problems with the vehicle only running for a few seconds the porblem being something with fuel delivery but since she runs for a while I'm thinking something electrical/sensor related. Any advice on any other place to look is greatly appreciated.

Thanks

Don't assume anything.

Any check engine light? If so, pull codes.

Test your way to a solution. I'd start by verifying and load testing your battery. A marginal battery can create a stalling condition.

You really should get some fuel pressure numbers. Need a gauge to tell you where you're at. It goes onto the schrader valve on the fuel rail. They can be rented from many parts stores. Compare your numbers to factory spec. If it were mine, verifying solid fuel delivery would be pretty high on my to-do list. Watch the fuel pressure and see if it drops as you lose rpms and the engine dies.

Cleaning the throttle body and the idle air control is never a bad idea.

This does not sound like an NSS issue.

Thank you very much for the reply. I'll work on getting those fuel pressure numbers.

Well looked at it and things were pointing towards fuel. Was too late to go to store and grab fuel pressure gauge. Just looked underneath to see a 146K original fuel filter and a waterproof connector that wasn't stock that connected to the fuel pump. I disconnected and then reconnected the fuel pump wiring. Lo and behold no more stalling. Something simple as a weak connection was giving us all this headache. *shrug* Who knew?

Sounds like you are on the right track.

146k and original fuel filter? Not a good idea. I'd get that fuel filter out of there ASAP. Yours I believe is on the frame rail and easy and inexpensive to replace.

Also be sure that the suspect wiring and connections are perfect and tight. If disconnecting and reconnecting it helped, your problem could return.

When was the last time you did a tune-up on that thing?

ah being my friend's jeep I'm just getting past teaching him how to do his own oil change. ^_^ Can't say when the last tune-up was. I know the sparks plugs are good I checked and gaped them a few months ago, the spark plug wires are about the only clean thing in the engine bay. It's getting the oil spitting back into the air filter and the typical engine tick. If we both weren't in the Navy on alternating schedules I'd be able to dedicate the proper amount of time to it and help get that thing in tip top shape.