Question for those familiar with 97+ XJ fuel issues...

[Gjeep]

This is probably a no-brainer, but I want to confirm with those of you who have experience with 97+ XJ's 4.0L's. As posted in my 'other projects' page, my '97 has been having idle, acceleration, bogging issues.  Runs rough and doesn't move as quickly as XJ's typically do. Just to cover the everything -- this is a low 37K 4.0L, AW4, 2WD. One owner, super clean. I installed a Borla header, magnaflow CA appropriate cat, and Borla cat-back exhaust. U-shape intake manifold, all new sensors (read every single under the hood sensor), new Champion spark plugs, Bosch 12-hole injectors, K&N intake, waterpump, thermostat, belt...and new Bosch fuel pump/ sender I got off ebay that was new. I've only recently driven the car, but has idled crappy since I've upgraded things which is frustrating.

 

Project took some time and basically sat for over a year... fuel went bad, and caused issues with the first set of 12-holes, but I've replaced them since and drained all the old fuel. At first the CEL had 105 (MAP) and 5 and 6 cylinder misfire. I had what I thought was a Mopar idle speed controller I purchased off ebay in Mopar box but upon closer inspection was a knock off. Replaced that with a true Mopar one and the former CEL codes went away. Once I replaced the injectors, fuel and sensors, if I don't push the jeep (meaning barely touch the gas pedal) it runs more or less ok with only an occasional CEL (now that either doesn't have a code or will register as a 104 (MAF) which doesn't make sense because the 4.0L doesn't have one). However, the second I mash the pedal...instant no power/ choking. Really feels like it not getting fuel. So I attached a fuel rail gauge to my '97 XJ and '01 XJ which is identically equipped except for 4-hole injectors and a coil-pack vs distributor.

 

I’ve been hoping like hell it is/ was something else because dropping the hitch, fuel tank and all the other $h!t isn’t fun. I took 3 reads on the 97 XJ. About at 42 lbs to start at prime every time and after 25 mins pressure dropped to 40 lbs.

 

 

 

I took 3 reads on my 01 XJ and it had about 48lbs and 40lbs after the same 25 mins. This pump has around 275k on it since it was replaced with another Bosch way back when.

 

 

 

These truck are supposed to be at 49lbs plus or minus a couple pounds.

 

What experience have those with this year XJ had with problems similar to mine. Looking for feedback. Pretty clear I needed to drop the tank but want to make sure I didn't overlook something simple. Thanks!

[89 MJ]

Yank it out and swap in a Renix system.  

[derf]

Did you replace the filter?  With bad gas, there may be junk in there.  I don't remember if you can do that without having to drop the tank.  Also, the pressure regulator is back there somewhere and it may be partially clogged.  If that doesn't do it, then you can drop the tank and replace the pump.

[Gjeep]

The filter, regulator, sender/ pump is all together...in the tank for it. Going to bite the bullet this weekend. Thanks

[Gjeep]

Swapped the pump/ sender in the tank which got my 49lbs at the fuel rail back and miraculously found a damaged pin on injector# 4 not allowing full contact with injector side so added to the horrible idle/ CEL. Life is good with the XJ finally.