[Kilby]

Vehicle: 1997 TJ 2.5L

Engine mods: cone filter intake on 4.0 tube, electric fan. Everything else is stock.

The basic problem is this:
After the engine has warmed up a bit, there is a definite lack of power and rough acceleration/stumble specifically at 3000 rpms. ESPECIALLY obvious when I've got the hammer down, then let off it a little, then step back on the gas. When I get BACK ON the gas, the motor has the hesitation and roughness associated w/ LEAN fuel mixture. The Check Engine Light error code that displays is 51...the one that says, "Lean condition detected".

Right now, (before I start spending money on parts that may or maynot be broken) I'm running some injector cleaner thru it in hopes that maybe the injectors were just in need of some cleaning. Maybe I should switch to 89 Octane? (instead of 87).

I'm looking for input regarding possible problems w/ the fuel system... ie, injectors, fuel rail, pressure regulator, etc. Has anyone experienced similar problems?

 

[RKCRAWLER]

I have a 98 w/6popper and have never had any problems out of mine?? Try the fuel filter. Or it might be some bad gas(water)?? Did it just start?

 

[Kilby]

Is the fuel filter serviceable on a TJ?
I think it's an IN-TANK unit.

Haynes :flipoff2: says it's not "fixable"...

Anybody done it? I can't imagine you'd have to buy a whole new tank just for the filter... but, then again, it is Jeep.

 

[cbhsbro]

filter...

The filter is an in tank unit. You can buy a rebuild kit for it, but you have to drop the tank and its a real major pain in the . I had to do it on my 97 TJ after it had set up for two years, I would try everything else before you go and buy the rebuild kit. Good Luck..

Chase

 

[nasvik]

What about the cat? Or the O2 sensors? Or even a rusty tailpipe? Sounds like it's making adjustments for something, and if that's the case I'd guess the rear O2 sensor.

Paul

 

[Kilby]

Well... that would be one of my guesses as well, but I just replaced the cat, TPS, and both O2 sensors in August.

The replacement sensors were not "factory parts"... Would they go bad again that soon??

 

[Rio_Grande]

I am fighting with this as well. I found that I had a leak at the junction of the exaust manifold and the exayst pipe, I fixed that, and still did not regain my power back, after replacintg plugs and wires, I pulled the ground off of the battery and let it sit over night, and I now have most of that lost power back. I am replacing the cat and o2 sensors this weekend in hopes that that will give me bac the rest, Right now top speed is 65 MPH with good gas.

 

[PavementPounder]

Have the spark plugs been changed at all? This sounds exactly like what my camaro was once doing and it ended up being the spark plug sleeves on 2 and 4. Other than that, it's gotta be the fuel system. Hope for your sake it's not the filter

 

[indyTJ]

2.5L problems

I have the same Jeep same problems and the same codes. I tried replacing the fuel pump/assembly... nothing. O2 sensor, nothing, cleaned throttle body, fuel rail, nothing.
I cut off my exhaust, beat the charcoal out of the CAT and welded it back on. Runs great now.

 

[4wheelnDutchman]

It's the fuel unit in the tank.. be shure you get it back together GOOD though... vaccum pressures can be tricky on that ol thing.
BbqBlake changed his 3 times before it worked right. but that was the problem... same symptoms.
-Bewarned dropping the tank is not fun!
maybe do a CJ tailgate and/or raise the tank up at the same time

 

[TexasBlake]

My YJ was doing that and it ended up being the fuel pump. The reason it probably says "lean indicated" is beacuse you arn't getting any fuel.

Get a fuel pressure guage and make sure it has the right pressure. If the pressure is still good, disconnect the fuel line at the rail, it should shoot a stream damn near across the driveway. If it just dribbes out, than it's a bad pump.

That was the problem with mine, I had adequate pressure, but no volume.

Dropping the tank on a TJ is gravy cause the leaf springs aren't in the way.

Also, if you replace your fuel pump, try to not run with less than a 1/4 of gas, thats what kills the fuel pump more than anything. And clean out your tank with some alcohol while you're at it.



But like mentioned earlier, it oculd be a clogged cat. Mine went out about 3 years ago, and it almost did about the same thing. Put your hand over the tail pipe and see how the flow of exhust is to check that.

 

[Steve N]

What Blake said.

 

[Kilby]

thanks for the help...

Here's another question.
Does anybody know where to get/how to build a FUEL PRESSURE guage for a 2.5L TJ? The fuel rail doesn't have a shrader valve on it. You need a setup w/ a 'T' fitting and extra hose to hook the guage into the fuel line...

The alleged auto parts stores here are no help at all.

 

[GPERX4]

How stupid is DC for putting the fuel filter in the tank, the more they make the worse they get at it.

 

[BBurris]

Re: thanks for the help...

Here's another question.
Does anybody know where to get/how to build a FUEL PRESSURE guage for a 2.5L TJ? The fuel rail doesn't have a shrader valve on it. You need a setup w/ a 'T' fitting and extra hose to hook the guage into the fuel line...

The alleged auto parts stores here are no help at all.

Does anyone have some way to test the pressure? I am going through the exact same problem - I know what to do, just can't figure out how to do it. I don't want to drop the tank unless I know that the fuel pressure is the problem for sure.

 

[Kilby]

FWIW... the fuel pump turned out to be fine. It was my broken PCV valve that I was ignoring that was causing all the problems (I'm stoopid). So I made one with some heater hose and it runs like a FREAKIN' TOP now.

 

[TexasBlake]

FWIW... the fuel pump turned out to be fine. It was my broken PCV valve that I was ignoring that was causing all the problems (I'm stoopid). So I made one with some heater hose and it runs like a FREAKIN' TOP now.

I thought that new Jeeps didn't have PCV valves? I know my YJ doesn't, it has a CCV vent... but it's not a valve.

 

[Kilby]

Okay okay...
it's not a "valve". It's a vent. Whatever it is... IT NEEDS TO BE CONNECTED.

I fixed it w/ some heater hose & misc. plumbing fittings.

 

[TexasBlake]

Okay okay...
it's not a "valve". It's a vent. Whatever it is... IT NEEDS TO BE CONNECTED.

I fixed it w/ some heater hose & misc. plumbing fittings.

Damn that's weird. I ran without one once, and all it did was blow oil all over the fawking place.

Must be a TJ thing. :flipoff2:

 

[Kilby]

Well... yeah. For about 6 months mine just blew oil out...

But I guess over time it screws up the system. Jeep thing I don't understand.