Yo-Henry

Hi there,
I’am from Germany my name is Yo and have a master problem with my cherokee xj 93 4ltr. and I hope you can give me
some support. My Cherokee starts normal, and have a normally idle, I can ride
sometimes 100m sometimes a couple of km till the engine goes out and didn’t run..
he goes out immediately, without any sign before,,.like stutter. after a while, I can start it normally
and the game starts from beginning…
its relay funny if you ride down the hill without steering power and breaks.
So I change following items:
Compl. Distributer with all ignition cable
Coil ignation
CPS
MAP
TPS
New lamdda sensor bevor kat.
Fuel filter
I check all cable and connection, found nothing..
When I start ignition, I hear the sound of the fuel pump,, its seems the system has also
Pressure, because when I push the valve in the near of the rocker cover, the fuel will make a fountain…
Can you support me with some inspirations what can I anything do ??
It will really a big help for me..

Thanks and warm greetings from Germany

dac612

It still sounds like a ckps (crank position sensor) which brand sensor did you use when you replaced it? This is very important actually. The aftermarket is hit and miss whereas the Factory mopar units are 99.9% success rate.

Could also be a lose wire or connector or failing asd relay or fuel pump relay, just throwing some ideas out there to take a look at

Yo-Henry

First at all, thank for answer,,
I first replace a after market part,, then a original mopar CPS. But the problem is still existed.. What you mean with ASD relay 😳?

dac612

asd (auto-shut-down) relay is what will provide power to the injectors and coil when it is time to fire.

The ecu will ground the relay which allows it to power the injectors and coil when it get signal from cps.

If this relay is faulty it can cause problems like this. there could also bea short elsewhere that causes the ecu to not ground the relay therefor no power to injectors and coil.

easiest to check for these problems when you the jeep will not run.

check reasons why not running. sounds like you have fuel pressure.

Next figure if you have spark or not during the no start problem. Then you can figure out why.

Yo-Henry

Whow,,,, Never hear that before !! Can you show me where the and relay is located ? Here is a picture of my relay box....
Don't know if it's any different from German types to US types

dac612

check underneath the cover there should be a diagram printed on the plastic pdc cover.

i believe it is the 3rd relay counting from the bottom

Yo-Henry

Many thanks Dac, will check tomorrow, because here in Germany is deep in the night...
I hope I will find it,, if it's okay by you, let us stayin contact....

Yo-Henry

Hi Ho, I check all the relays, all of it was oky,, exept the FAUX VAN ! so i take a new one in... also I check the fuel presure, its fine, its (sorry german) 3 bar, my book of "help your self" says it will be okay....
so,,, anything looks fine,, but why died the engine on the road when iam driving ??? have anybody here a contact adress from a exorzist :-) or maby a other idear where I can look at it

dac612

Hey there. Good job on the relay checks. I was re-reading your OP to get an idea of when this happens and it seems you can always get it to start when cold right? But after driving for varying amounts of time then the problem happens? Makes me think some core component is getting hot and failing then works again when it cools down.

My advice is to get very familiar with all of your readings and checks when the engine is cold and you are able to start and run.

Then do all your tests again when the engine dies to see which one is a miss.

There are a lot of items that can start to fail when they get hot but then seem totally fine when they cool down.

The main ones to look out for thermal failure are:

crankshaft position sensor.
camshaft position sensor.
ignition coil.
fuel pump.

Yo-Henry

hi dac, hi everybody,,,,at the moment anythink looks fine, dosent matter if I start cold or in warm condition it runs fine... but Iam scared to drive... remember last time it stops without any sign, like you turn the key off..... and thats in the mountain not realy funny !
so today, I make a fuel pressure test again,, so I figure following out:
put the test manometer to the valve, enginge is sill not on... NO presure ! turn the key but not start,, so pump makes nois,, bsss... for maybe 2sec. presure is up to 2 bar... but the system can not hold it.... so turn the key 3 times (still not strating the engine) presure gos to 3 bar... but still not holding the presure... Then I start the engine,, runns fine,, presure 3 bar... turn the engine of and watch whats happend with the pressure,, fall down to sero....
now I think I have two opptions,, the system loose the pressure,, but where ???
ore, the fuelpump is no good anymore... every idea wellcome !

dac612

OK, sounds like you are on the right track.

The bleeding down is mainly caused by 1 of 4 things.

1. Fuel pressure regulator leak. (this will leak down into the manifold) through the vac line that runs to the regulator which is located on the fuel rail (near front of engine).

2. Injector leak. This can be easy enough to test. Leave the injectors clipped to the fuel rail but unbolt and remove the fuel rail from engine( be careful so you don't hurt the o-rings) takes a bit of force to get out. Use a towel or container in case there is a large leak so you can contain the fuel. Turn the key to on to allow the fuel pump to prime. (do not try and start engine) No fuel should come out of any injector. If it does. rebuild or replace leaky injectors.

Another way to check is to leave the injectors in and clamp off the return and feed lines after pressurizing to isolate the injectors but it can be tricky to clamp off the old lines up top on these xj's without hurting them.

3. Leak in fuel line somewhere. Just follow the lines looking for the leak / any wet spots

4. POSSIBLY the rubber hose inside the tank and on the sending unit that runs from the pump to the hard-line has deteriorated.

As far as the low pressure and eventual stalling when driving. Could be the fuel pump is about done would replace fuel filter while you are at it.

Yo-Henry

Thanks dac,, will try everythink and report whats happend,,,
by the way,, this is realy a great forum.. have a nice and good weekend

Yo-Henry

Hi there,,
Hi Dac
yesterday I check all the above thinks in the recomented way,, all fine,, fuel regulator, all injectors found nothing,, no leak, but in this stage I cleaned all and replaced all the O-rings.. so put all together and try the presure. It loose again,, but not so quick as before.. so I take a look at the fuel line and... found one !!! I will replace it later today and will report..

Yo-Henry

Hi there,,
hi dac,, so fuel line is fixed,, but still loose presure, later today I will take the pump out, what Iam dount understand is, when the engine is running, the fuelpresure is fine,, about 3 bar when enging is running... I install new O-rings and a new presure regulator, also the fuel line is fixed,, I see no leak somewhere.. so, where I loose the pressure when I turn the engine off ? can it realy be the pump ?? because it makes pumping nois when I turn on the igintion and also when I start it makes a presue of 3 bar.... any comments very wellcome

dac612

OK good job.

How much bleed down are you getting? As long as it stays 25psi or better after 5mins after you turn it off. You are ok.

to continue on to your stalling issue I want to focus on this line from your original post.:


after a while, I can start it normally and the game starts from beginning…

How long is awhile would you say? 30 mins? 4 hours?

Some critical component is most likely suffering from thermal failure. When it gets hot it stops working correctly.

The items that generally can cause a stall scenario are. Do not rule out even a new component. Electrical components even new ones can die unexpectedly. It has happened to me more than one time.

Crankshaft position sensor
ignition coil
camshaft position sensor (inside distributor)
Fuel pump.



You have done a good bit of testing but you need to do some right when it stalls to find out what has died or what has changed...