I just installed a new Crank position sensor on my 98 XJ and Im still getting the same symptons as before. It never starts on the first try and stutters and stumbles half the time before it does start running right. Could it be my CAMshaft position sensor? What else could it be? B y the way, replacing the crank position sensor was pretty easy, didnt even need the elbow joint adapter as mentioned in the write up. then again, my jeeps lifted a little bit so Im sure that made things much easier.

 

Bumpdate! First off NEVER BUY A CPS OFF EBAY!!!

After installing a $30 ebay CPS my XJ would buck and hesitate during acceleration and was overall running like but. I'm assuming that's why it still didn't start on the first go round. I guess ill be buying another CPS from autozone. I'm still waiting to hear back from the ebay seller...pray for me. I'm pretty pissed about the whole deal. So...any other ideas on why the XJ won t has trouble firing up? Are the fuel pumps faulty on these things?

 

A cam sensor could cause the same problem, so could a bad fuel pump. Put a fuel pressure gauge on the fuel rail and check the pressure while the engine is running, then shut the engine off and let it sit for a while. If the pressure bleeds down to nothing, you have a faulty fuel pump check valve.

 

Okay so I installed a different Crank position sensor from NAPA and Im still having problems. If I cycle the ignition it will almost always fires up on the first try. What controls how much fuel is primed into the engine to start it?

 

is it showing any cel's? If so i would definitely get those checked. Also try the throttle position sensor. That went bad on mine and it wouldn't start and ran like crap. That one is like a two second and $20 fix

 

It shows a check engine light intermittently but hasnt since I changed the CPS. Would the throttle position sensor be the problem if I can cycle the ignition and it starts right up?

 

No, the fuel pump is the problem.

 

ans by problem you mean its on it way to taking a ****? Any popular upgrade from the factory pump when these go south?

 

Try this...
I had a long start PROBLEM, and after alot of reading and a little help from a good friend (hooked up a computer and looked at all the vitals) we figured out all I had was a fuel pressure reg problem.
BTW: I really think this is your problem because mine ALSO stumbled alot before it started, thats what got us thinking it was flooding out, I know, how does a FI vehicle flood???
Two things we could think of...1) bad injector leaking by or 2) fuel pressure regulator leaking by...the vacuum line goes DIRECTLY into the intake manifold...so it turns out it was leaking and causing flooding symptoms!!

https://www.cherokeeforum.com/f2/xj-...-53438/index3/
I figured out my long start problem.... Turns out my Fuel Pressure Regulator was leaking by the diaphram into the intake and flooding out the engine, not to mention depressurizing the fuel system. figured it out by turning the key to on a couple times to pressurize the fuel system and taking the vaccum hose off the regulator and VOILA it was leaking fuel! new regulator installed and now im back to quick starts!!

 

There is no fuel pressure regulator on a 98 Cherokee, it is a returnless system. The amount of fuel used for each injector is controlled by the pulse width time the injector is open, so is computer controlled, not vacuum controlled.

No real upgrade for the fuel pump, just replace it with a quality brand such as Carter.

 

I am having the same problem... Long time to start, but once it is running it's perfect. What do you think, fuel pump?

 

ooops.
Learn something new every day, sorry bout the bad info... didnt know about the returnless system. Thanks for the upgrade bustedback.

 

If you have only one fuel line on the fuel rail, you have a returnless system. I think 95 was the first year for the returnless system.

 

thanks for that info, thats def. something Ill look into. Could I take the Jeep to a dealer and have their computer tell me if its the fuel pump also? What computer did he use? Was it some kind of laptop setup or a scantool?

 

M4RK
He used a Snap-on MT2500 scantool
Here is a picture and some links to a few.
As mentioned above, I did not realize you had the returnless system. Since mine is a 93 and a return type fuel system I have a fuel pressure regulator, I dont believe you do though.
Snap-on web site:
http://buy1.snapon.com/products/diag...01&dir=catalog
E-bay:
http://shop.ebay.com/items/snap%20on...p_id=668070407
Video:
http://showmetools.com/?p=30

PIC: