94 xj 4.0L so recently the motor just cuts out and acts like its outta gas while driving, it also happens sitting at a stop light at idle. sometimes it hesitates but keeps running. other times when it dies it wont start right away, it takes a minute or so before ill try to turn over again and will start up. I havnt checked for fuel pressure yet or possible a spark issue, but in 2013 i changed mostly all of the spark related parts, coil, coil harness, dist., dist. pickup, wires, plugs, oddysee batt., also replaced as much vac line i could get to. Has a KN intake system from prev owner, passes smog. Also flushed cooling system/ replaced sensors. replaced fuel filter too. any suggestions what I should trouble shoot first?

 

Mine '00 would stall when driving it a little after it reached operating temperature. But would start back up. No CELs or pending CEL's. I did not check the fuel pressure because it would cut out. Like you turned off the key. Not sputter and die. So was leaning towards it not being fuel related. Took a chance and replaced the CPS. Been a couple days so hesitant to claim victory but so far so good.

https://www.cherokeeforum.com/f2/cut...riving-241745/

 

Thx Ralph77 for the suggestions, I guess my bigger issue is why its stalling not necessarily why it takes a minute to restart (think both my problems are related though)

Happens after it gets up to temp too and does 1 of 2 things, First thing I've already explained (just stalls and takes a minute to restart) and second is I'll turn it off for 15 minutes or so and upon restart it runs like its about to run outta gas, kinda sputters and if you push the gas pedal it stalls. When this happens it will restart right away and seams to run just fine (this also happens sitting at a red lite or drive thru)

I sure hope the CPS was your fix cause I know how difficult it is to replace but please correct me if i'm wrong, the CPS only triggers TDC upon initial start so that doesn't explain the engine stalling, and my last xj I had when the CPS failed it would not restart.
Come to find out that the CPS was replaced in 2012 by prev owner and I'm still not ruling out changing it but like I said, why is it stalling?
Any additional input would be great!

 

The CPS monitors the crank position continuously, feeding that information to the computer to use in engine operation. If it is going (meaning kinda works but is on the way to total failure) it can cause stalling. It taking a minute to restart is likely due to heating/cooling of a failing component or a loose/corroded connection that's having trouble conducting electricity.

If it were me, I would start with cleaning and tightening your grounds. The ones in the engine compartment as well as the 2 behind the driver's side trim panel in the trunk.

Once you are sure that your grounds are clean and tight, the next thing that I would check is fuel pressure. I would do it when the engine is cold and if possible, when you get the sputtering behavior. It needs to be a solid, continual 49.2 +- 5 psi.
I would do these steps first because they are both basically free (you can rent the fuel pressure tester at Autozone with a deposit) and they are both a lot easier than getting your CPS off. Cleaning and tightening your grounds is something that you should be doing as part of routine maintenance, but is often overlooked.

 

What Pat said, check the free stuff first.

I have the same symptoms on my 99 and it was the CPS.

 

Personally, if it were me (after doing the free/easy checks) I would probably just buy a new CPS and install it.
There was some great insight from Jordan96xj in another post discussing the difficulties of -properly- testing the CPS (in short, it's not as simple as taking a multi-meter to it). So considering that, plus the difficulties of getting at the part, plus the fact that in the OP's case it's an aftermarket one, it would be worth the $60 or so (for my year) to have a new one and only deal with the removal/replacement once.

 

It also costs nothing to take a good light and inspect the CPS wires. There was a guy in another post that replaced his CPS but didn't secure the wires and totally fried them. The point is that if you have a wire that the casing has cracked or ruptured, it could be occasionally shorting out and hence messing with the proper signaling.

 

I went food shopping yesterday and all seems well. It was guess that it was the CPS from googling about it and the help of some of the forum members, got love the forums, but was still just a guess. While I try not to randomly throw parts at the Jeep I justified doing the CPS like this. I am the 3rd owner. I figure that any part that I have not replaced personally is original. With 160K on it. So.......

 

Thx everybody for helping me with this. So i've cleaned and made sure grounds and connections tight and secure. The sputtering occurs when up to temp and dont have the chance to check fuel pressure
safely. I do own a fuel pressure gauge as well as a vac gauge. Its reading 35psi at idle and will go up to high 40's when i hit the throttle and 15 on the vac. I'll get those readings weather the engine is hot or cold and of course it wont sputter when i have the gauge hooked up. I did more research on CPS and got a better understanding on its function as well as the info everyone sent me, going to change it with a mopar one!
I dont want to be stuck on a trail!
With all that being said I think there still is a fuel issue that I need to hunt down!

 

What's the pressure spec for 94? That sounds low for fuel pressure...

 

so i checked the world wide web and dummy manuals for fuel pres specs on my 94 and they all come back saying the same thing,
95 and earlier models MPI systems should be 31-33 psi (my gauge reads 34)
with the vacuum tube detached from the fuel pressure regulator should be 39-41 (im at 42)
with the vac line detached there should be a 8-10 psi difference indicating fuel pressure regulator operating correctly (im at 8 psi difference)
my psi is slightly higher but the gauge i have is a cheap one!
(96 and newer models psi range is 46-51) so i ruled out a fuel issue for now.
new mopar cps on the way, luckily I've changed one before so I know what i'm up against.
thx again for everybody's help, will post results after new cps goes in!

 

Sound good - good luck!

 

So I have replaced my cps on my 97 grand cherokee laredo and have checked grounds and I am still having issues any ideas on what else it could be?

 

Are you having the same problem as the OP? Did you check your fuel pressure? The spec for 97+ is higher than the prior years.

 

Hello Civic. Same problem with my 94 4.0. Fuel pressure and CPS checked out OK. Auto shut down relay replaced, new plug wires, new cap and rotor, problem persists. Two garages looked at it and "fixed" it, but still same problem. Spent $1000 total with towing when it broke down on a turnpike. Did you find a cure? At wit's end.