When driving my 94 4.0 high output automatic xj will occasionally stall out, if im driving it will start back up, if im at a stand still it will need to be turned over. I've done a fuel pressure test, jumping the relay it peaked at 40, disengaged jumper held at 35 and dropped to 23 after 5 minutes. After that I did a running pressure test, it held at 32 running and jumped to 40 and held when I disconnected the vaccum hose for the fuel pressure regulator and when I let it sit for 10 minutes it lost 7psi to 25 from the 32 it was holding at running.

 

Posting twice about the same exact issue is not the ideal practice for these forums btw. 3 hours isn't very much time for some of these fellas to make their way into the threads.


I did find this on Naxja though and you can also click through thr link to read into the full diagram.

" If engine runs, but pressure is below 44.2 psi, check for a kinked fuel supply line somewherebetween fuel rail and fuel pump module. If line is not kinked, but specifications for either the Fuel PumpCapacity, Fuel Pump Amperage or Fuel Pressure Leak Down Tests were not met, replace fuel pumpmodule assembly "


https://naxja.org/threads/fuel-press...ule%20assembly.

 

My apologies, I posted it in modified xj section, realized I made a mistake and reposted in this secton, I will remove the other post didn't cross my mind at the time.

What are the odds the cps is causing the the stalling?

 

The thing about the CPS is that when it starts to fail or cause problems it typically is a bit more dramatic than just a sudden shut down but then immediate re-fire. The norm for when they start going bad is for you to lose spark for periods of time after it warms up or maybe even before it's warmed up. 5-10mins it's basically until the sensor cools down; Dex Jeeps or DexJ on YouTube had a video about it showing a faulty cps and how he could hit it with cool water and he'd get his spark back immediately because it cooled the sensor down.

For you to have this sudden shutoff but then quick re-fire idk. Check grounds and battery cables. I've had a situation where the section of harness around my battery and alternator/coil would wiggle around and kill the spark. While your jeep is running get that hood open and wiggle/move wiring around and maybe you will trip w/e you potentially have for a wiring issue