Flexy or someone with ZJ knowledge

[JamesT]

Is there two fuel filters on a '94 Grand (5.2l)?

I know there is a big one back by the tank, but is there another one up further in the system?

TIA

[Linda]

Is your son still having starting problems with the ZJ?

[JamesT]

Originally posted by Linda
Is your son still having starting problems with the ZJ?

Yes, he has replaced a bunch of stuff now.

Here is the latest:
It will start first thing in the AM or after sitting for a few hours. When he trys to start it after driving it is acting like it is flooded. Pumping the gas pedal gets it started, then when he puts it in gear it stalls.

One thing, among others, he did replace is the IAC.

I told him next time it starts acting up to drain the pressure from the fuel rail and see if it starts. Since the IAC was replaced and "supposedly" he is getting enough air, then maybe it is getting too much fuel. He also replaced the regulator in this last round of fixes. Also, this scenario kind of makes sense, if it sits there for long enough the pressure bleeds back.

So if letting the pressure out solves the problem, my next question is going to be, what would cause the pressure to be to high?

{Edit} Maybe he pinched the return line (?), but why wouldn't the pressure build other times?

[Linda]

Did he ever test or replace the TPS?

[JamesT]

Originally posted by Linda
Did he ever test or replace the TPS?

I am thinking we replaced that during the last round and it didn't help. All these letters are starting to confuse me.

He is going to live with the problem for now and then come down on spring break. It is too cold to work on the thing in the snow with no garage, I am sure the lack of tools doesn't help him either.

[FlexyXJ]

Originally posted by Linda
Did he ever test or replace the TPS?


James, Dont waste $$$ on a TPS.( throttle position sensor) There is one EXTERNAL fuel filter, which is the one you replaced, (doutful its the prob) There is a "pump sock" on the pump itself. (doubtful prob) First thing first....put a fuel pressure guage on it. If its a 94, have you checked the codes by cycling the key?? So many possibilities, you just need to do some diagnostic before you throw parts at it.


Joe

[Linda]

What he really needs to do is sell it and find pre-1988 4x4. Those usually don't have a computer onboard. Those computers sure make things complicated! Diagnostics are more difficult and the wiring harness schematic takes more than two pages in the FSM.

[KevinF]

Joe is right...check the codes and see what it spits out at you. I've had one do this that the coil was going bad on, but I think it was an isolated problem. TPS and it's associated wiring harness might be a good place to start checking. Best thing to do is to buy the shop manual. It's about $75 and worth it's weight in gold. It gives you step by step troubleshooting on problems like this.

Cycle the ignition three times on-off and then leave it on the last time to get your codes. Read the flashing light on the dashboard. Twice then a pause and then three more blinks would be code "23", and so on. All codes are in the manual, or at www.nagca.com, or Joe or I can tell you what it's trying to tell you also.

Good luck. Kevin

[JamesT]

First, thanks for all the replies....

Second, my son has the manual.

Third, he said, it isn't flashing any codes. We wil check it when he get down here, again. Kind of hard for me to believe.

Forth, released the pressure in the rail when it was acting up and it still didn't help. Shoots my idea, clear to heck.

Fifth, my son needs to take Linda's advice about a non-computerized vehicle. ;)

We will see....

[JamesT]

Well I just got done messing with my son's ZJ.

No codes were being flashed, so I started kind of blind.

First and easiest, I found a plug wire off the dist. He said, it must of fell off when he was replacing the regulator. It is beyond me how someone can drive a vehicle with this loud ticking going on and think it is ok. Anyway.... this didn't fix the original problem.

I checked the voltage going into and coming out of the TPS, it was fine. I check the voltage going into and coming out of the MAP sensor, it was all good. I ohmed out the coil, no problems. the vehicle still acted the same.
I took off the IAC and was messing around with it, trying to figure out how it works, just like an "engineer" (it is an intersting device). I pushed it in and reinstalled it and the problem was gone.
So I think I found the problem. We have to take it for a drive again and see if it will fail. According to the manual there is not a "for sure" way of testing it. It seems like the hotter the engine gets the less the IAC is retracting, thus flooding the engine.

Anyone have any experience with IAC's?