1993 XJ 4.0. List: new everything pretty much (engine, injectors, wires, sensors, plugs, distributor, cap..) and runs like new 99% but the past couple days when under load and climbing a hill it fells like I turned the key off and it stumbles. I fluttered the gas pedal and it will recover then run fine again. Alternator charging and checked all my grounds...and connections. Fuel pressure is at 34lbs at idle and drops to 25-26 at rev to 2000rpm. I'm thinking dying fuel pump (new fuel reg and filter). Please chime in with your thoughts...I help when I can and this is the first place I look for need to know with my XJ. And any help is appreciated! T/Y

 

66 views and not one reply...

 

Give us some time, there are many many threads...and maybe the ones looking at your thread are curiously checking for an answer to your question.

I know PSI for my year(s) should be around 49 +/- 5 PSI. Yours is lower IIRC, and the one at idle is not too bad, but the 25 at 2000 rpm's seems (too) low.

New engine...was it swapped for another year or remanned?

 

yeah but it's been a day since the post..just saying. Thanks for the reply though. It's a reman of same year 4.0 HO. I didn't get any responses so I decided to purchase a fuel pump and will put that in this morning and see what happens. I hope I made a good call~ we'll see

 

In my experience.. I have yet to run into a weak fuel pump.. I usually find that they work, or they don't. Doesn't mean its not possible.. just haven't seen it.

 

Okay. So installed the FP on Friday and on the ride home it didn't miss at all but on the ride to work the next day.. under load and uphill it spit at me again.. it seems to lose power at mid range as if running rich and in limp mode on long drives. While in town it runs freakin' great. One thing I left out was I replaced the fuel injectors with some ebay remans a month ago and after install two of the six injectors were faulty and had to replace with two new retail injectors and has been running great 99.7% of the time. The other % is as described. I'm thinking now maybe I have another faulty injector, causing it to run slightly rich. I've checked all the plugs and none are apparently bad or fouled. Any ideas anyone?

 

Your CPS, you said new sensors...also replaced that one?
And have you checked for codes at any time?

 

I did replace the CPS but about a year ago. Previous to having my shop replace the motor. No I haven't checked for codes, that may be the only thing I haven't learned to do. Someone said it may be a waist of time on the OBD 1...?

 

Ahhh...1993. Top be sure, I don't have experience with codes and the OBD I, but some plenty of members around to fill you in on this.
That CPS, brand does matter unfortunately...OEM is recommended, since the aftermarketss are unreliable.
Are you confident your replacement injectors are now all in good working order now?

 

I know what you mean with the CPS. When I replaced it I got one from Oreilly's and the first two off the shelf were crap... lucky number three fired right off. I do have a new Mopar CPS sitting on the shelf as back-up tho.
And no, not sure all the injectors are firing properly and that's my next process and purchased a set of new from fivemotorsports. I'm hoping to get them by tomorrow. I'll replace the plugs at the same time and check for slight misses. I hate just throwing $ at it but my skills trouble shooting injectors is nil to none except checking plugs and swapping out but I'm fairly confident one or more of the remans are faulty still.
Thank you for all the help gentlemen. if you have anymore advise I'm all ears and thumbs. I'll keep you posted!

 

Okay here's an update..
I installed the injectors a week and a half ago and while I was at it I cleaned the TB and swapped out the TPS. I noticed I may have had a leaking TB gasket and replaced this as well. So far no problems
I really like these new 24lb injectors too and can't say to many good things about the ebay remans at all. Idles so smooth now and even have begun to see a possible increase in mileage...I really can't say for 100% but I'd say it was one of the injectors for sure and was definitely time for a new fuel pump. Thanks again for all comments and all help~

 

Thanks for giving us a play-by-play description of what you did. I'm sure this will help out someone with a similar problem in the future.