Evil in-tank fuel filter robbing my MPGs and power

[JeepNmpg2]

2000 Jeep Cherokee with the I6 engine has been really good to me overall, but as I get around to doing some much needed maintenance I'm running into more and more problems (things I've all but ignored). I just replaced my old worn out stock injector (single big hole) with some new injectors that sport 4 holes and the same flow rate as the stock ones but supposedly provide better fuel atomization (snake oil?). I noticed some deposits in my fuel rail that weren't fuel, but some collected rust that had moved it's way from the fuel tank to the rail ala worn out filter but just cleaned it up and went on my way. After installation of the new injectors, I drained the capacitors on my SUV and reset the computer so it could learn the new injectors. Mileage was pretty crappy for the first 50 miles or so, but it picked up suddenly after that by about 1.2 MPG (me watching the gauge, not any other real method of measurement). I stopped the vehicle for the night and during my trip the following morning, I threw a check engine light and ran the code to find it to be a missfire in cylender four. Granted this is one of the "catch all" codes for my vehicle so I went through the motions and checked (and changed) the spark plugs, checked the PCV and other vacuum hoses that were temporarily moved during the installation. I begrudgingly pulled the fuel injectors and found a huge collection of sediment in the back of the injector and flowing in the rail. Basically my in-tank filterscreen is blown through. The engine will continue to throw that code whenever the engine is idling but it goes away while under power. Under power however, it is really lacking (basically it's running on default maps in limp mode). I'm not over advocating "seat of your pants power" but you can really tell a difference when your daily driver isn't behaving normally especially in a quick WOT 0-60 test. I've looked into the mess via online research, but either I drop the entire tank and skid (not happening short of pump failure) or I put in an inline filter to take care of the debris. I ordered a flomax 300
on Satruday and expect it to come in on Thursday. I'll take some pictures and post the installation on here.

[jakobnev]

Most (if not all) fuel injected cars have a hight pressure side fuel filter, in addition to the low pressure one mounted in the fuel tank. It is usually this filter which is clogged or broken if you engine can't get fuel or gets dirt from the fuel line.

[JeepNmpg2]

Here's a picture of the fuel rail pulled with the fuel injecters still attached. The fuel line is still connected but I had already depresurized the fuel system.



The second picture is all of the dirty fuel and debris that was in the fuel rail after I pulled everything off. I flushed it clean and scrubed any stuborn particles off until I couldn't get anything but fuel out of it. I did finish the installation of the filter but will get pictures for those later on.



I cleared the check engine light and it didn't come back which is great as well as the idle seems to have smoothed out a little. Only time will tell if the fuel filter does the trick. Being as I only had about 500 miles on it since the last time I had the fuel injecters out and cleaned/checked the fuel rail to accumulate all of that, not to mention what may have gotten into my engine.

I'll post more later!

[kir_kenix]

My '99 Cherokee 4.0L had a fuel filter on the rail. Might want to give it one more look down there, just in case. It only makes sense that a vehicle designed to be used off road, drove thru streams, etc that you would have an external fuel filter. If yours doesn't have one, shame on Chrysler for lack of foresight.

[kir_kenix]

Hey just wondering if you installed that filter yet? I talked to my friend who is a tech at the local Chrysler/Dodge/Jeep dealer. He confirmed that some 1999-2001 4.0 Cherokees did indeed come without an external fuel filter. Dumb system if you asked me.

He says this comes up alot, and there is a retro-fit kit from the dealer with correct mount, fittings, and OEM style filter. My buddy told me its a super common item, and their part department stocks 4-5 kits at any given time. Not sure what your aftermarket kit cost, but I'm sure the replacement filters for that thing are expensive.
If you are looking for a less expensive option (filter changes anyway), you might consider the OEM retro kit. Anyway, I hope either option ends up getting you back on the road man. Good luck.

[JeepNmpg2]

Already installed it, just have to button up a few last minute things (like proper bolts instead of zip ties, etc). I think I'm going to prefer this method for filter replacement as it's just like the oil filter and you simply unscrew it instead of having to mess with crimps and such. It also has the option to use one of the extra ports with a drain valve to discharge the system before removing the filter (instead of the relieve valve on the fuel rail). Filters are $20 or less and I don't anticipate replaceing them all that often, but we'll see how things hold up. Again, more pictures when I'm finished!

Already took the vehicle out in town in traffic, much better off the line feeling and it runs MUCH smoother now that it isn't stumbling over one of it's injectors. I may be making a longer drive the next week so I'll look into whether or not FE is affected by this, but it surely can't hurt it.

[Fat Charlie]

Both 99 and 00 XJs have a fuel filter/regulator on top of the fuel pump, p/n 4798301. I just went through Chrysler's system and didn't find any mention of changes to the fuel system. No parts nastygrams, no tech tips, nada. Can you get a part number from your friend, kir_kenix? I'm curious. Every shop has its little tricks to fix problems that they see but the factory doesn't. It looks like the factory doesn't see an issue here (they might, but that would take a lot of digging during the week), so this looks like one of those local fixes.