at wit's end!!

[dirtymuddog]

i just got new cpu this am, which i thought was the problem, now is doing same thing old comp was...it will turn over for about a second after fuel pump primes, then die. after i replaced the plugs, wires, rotor button, cap, crank sensor, throttle positioning sensor, fuel filter, fuel pump it ran like a champ for about an hour. i ran it all around town. then the next am i go to start it and leave, guess what? this problem. i put a test light on the injectors and it lights up, but then after initial ignition the sob dies. WTF? im at the point:explosion under the gastank if i didnt like it so much. oh yea more info..4.0 auto w/ 160k, and i cut the cat off in the process cuz it smelled like it was clogged. thanks for any help

[dirtymuddog]

oh yea i replaced the coil too. thanks

[Pioneer84]

Did you check the power latch relay ? its the second one from the left.

[Michaelarchangelo]

Check the fuel pressure on the rail? Maybe a clogged line somewhere?

[dirtymuddog]

i can check the pressure, i guess some trash could have gotten in line after i cleaned the tank when changing the pump. the power latch relay, its the second what from the left?

[Pioneer84]

On the passenger side wheel well you will see 4 blue relays one next to each other looking down at them from the passenger side its the 2nd one in from the left change it with one of the others and see if it works now if not it rules out the relay.

Ron

[dirtymuddog]

thanks, i think i switched them around already, but i might as well try again. thanks

[dirtymuddog]

anybody else got some ideas, im tryin to make a list of what i havent hit yet and start there. i checked my grounds, replaced my main one off the battery, that sob was ripped in all kindsa places. that didnt fix my prob but im sure it prevented some in the future

[langer1]

thanks, i think i switched them around already, but i might as well try again. thanks

Don't switch them around, I had two out of the 4 bad, get all new ones.

http://img.photobucket.com/albums/v11/langer1/jeep/FSM/relayscopy.gif

[rws]

Had the identical problem. I checked all the relays (4) according to the tests in the Renix manual and they all checked out good. I was at my wits end also and after checking all the componts you replaced (including the wiring) I determined that it could only be fuel pump relay so I replaced them all with new ones. Jeep now runs perfect.

[dirtymuddog]

thanks fellas, i guess thatll be my next adventure after work tomm am.

[dirtymuddog]

could it be the starter relay? it looks differant..most relays are box shapes that cost bout $12 and the starter relay cost $52?

[langer1]

could it be the starter relay? it looks differant..most relays are box shapes that cost bout $12 and the starter relay cost $52?
No that only effects starting, it's not used for run.
The cube relays should be about 1/2 that much at Napa or Autozone.

[outlander]

oh yea i replaced the coil too. thanks

Are you throwing the cat away that you sawed off?I'll take it if you still have it.

[dirtymuddog]

if i dont sell this xj after i get it fixed, ill let ya have it man. if i sell it they might want the cat, or if i use it as a trade in it might help.

[cdw25271]

hello check the white ceramic resistor or the fenderwell. i knocked mine loose one time while working on it and it would start and die a few seconds later.

[cdw25271]

on the fenderwell can't spell today

[dirtymuddog]

well its not wanting to start now, replaced the ballast resistor, thought that might do it...guess its time to buy relays and maybe the ignition control. if anybodys got any ideas, i dont care if it involves duct tape and mouse wheel, let me know! thanks fellas

[dirtymuddog]

i think i might take out the fuel pump too. its priming..just replaced it but my luck it could be bad...dunno

[90xj06]

you dont even need the resistor it was recalled for the 87's just short the 2 together. and see what happens.

[dirtymuddog]

just cut at the plastic head and splice together?

[dirtymuddog]

man now ive replaced my vacum assembly, there were some leaks in it...what about the egr siliniod? i replaced the vacum to it(its on the fender drivers side right under hood) the engine wants to start..bad..but doesnt. the engine is cold, but after trying to start it the egr was warm..could it be stuck in the wrong position to start? thanks guys, lemmi know if ya think of anything

[langer1]

And your fuel pressure was?
I think you need to spend less money on parts and a little more on test equipment.

[dirtymuddog]

the fuel rail is charging, b/c my plugs have fuel on them...

[langer1]

the fuel rail is charging, b/c my plugs have fuel on them...

But at the correct pressure?

[90xj06]

make sure the egr is all the way out. unplug the hose and blow into it. and suck on it. it should move.

[dirtymuddog]

i couldnt get anypart on the egr to move. i unplugged both ends from the vacuum harness, unbolted it from the fender, noticed there was some build up onthe cylinder, so i sprayed it with pb blast. then i started blowing harder than a $20 whore on both ends, nothin moved

[paintfiction]

I had a cHEVY cELEBRITY (stupid capslock key!) that would do a similar thing - start and then die. Turned out the EGR was plugged. Back pressure from the crankcase was causing it to die. I replaced the EGR valve ad everything was peachy. DOH!

[langer1]

i couldnt get anypart on the egr to move. i unplugged both ends from the vacuum harness, unbolted it from the fender, noticed there was some build up onthe cylinder, so i sprayed it with pb blast. then i started blowing harder than a $20 whore on both ends, nothin moved
The EGR is on the engine under the intake manafold, the valve on the fender is only the control and don't move.

EGR valve.

http://img.photobucket.com/albums/v11/langer1/jeep/FSM/egr.jpg

[90xj06]

becareful and suck on it. it should pull back. if not its stuck open.

[arkansasduck]

ya i dont know if u replaced the coil?? but i had mine tested a autozone and they said it was within omes and was good but quess what? it was bad? i bought a new one solved my prob. good luck

[8Mud]

A list of possibles from the sound of your problem, starts then dies, or starts hard, runs bad, then dies.
MAP unplugged either electircal or vacuum, vacuum line plugged into the wrong hole in the TB, faulty MAP. Barley starts and hard to keep running.
EGR stuck open, you can if your good use a pair of needle nosed pliers and make sure the EGR is seated all the way, if it is stuck sometimes just turning the rod from the diaphram to the stopper will loosen it up, sometimes you have to force the rod towards the manifold. Wiil start them die, if you can feather the gas pedal some and get it up into the higher RPM range it will usually run OK at higher RPM,s. Plug the vacuum line just before the EGR modulator, just for a test.
Excessive resisitance in the CPS wiring. Check yout new CPS for resistance, just becuase it's new doesn't mean it's good. I just swapped out a new one, because of excessive resisitance.
Hold a volt meter on the end of the ballast resistor. It should have volts both during start and run. Two different citrcuits until it gets to the ballast resistor, could be a bad splice. Like mentioned the fuel pump relay. But don't stop there, look at the relay holder also, they can get really corroded at the contacts.
Do a sync sensor test, not because the sync sensor is bad, but low input voltsge for the sync sensor is a sign something else is wrong, often a short in the sensor power supply circuit. Might as well test it for pulse while your there.
Fuel pressure or volume.
Problems are in the wiring and the connectors, even the grounds as often or more often than the sensors.
If the IAC isn't parking or is stuck shut, it might start, but you really have work the gas pedal to keep it going. Try starting with the gas pedal at about quarter pedal or a little less.
If the spark is really bad, it likely won't start or maybe just fire off of randon cyclinders and never really get going. An open circuit or excessive resisitance in the coil to cap wire and/or a ground short. Water in the ends of the cable boots.
You really have to be systematic or it gets real expensive real quick. I've got a whole set of junkyard sensors, just to test with and keep for trail spares.
The CPS bolts are special, swapping in the wrong bolt can cause a lot of grief.
You can be a cylinder off, when installing the distributor and it will run, maybe even two, more than that and if it starts, it won't likely run for long. You can have the same affect by having all of the calbes three cylinders or so off. The Renix is real forgiving in this regard, but it has limiits.
Good luck.

[dirtymuddog]

thanks fells, hopefully ill have enough time this wed after work to start on this process of elimination..thanks again, eric

[dirtymuddog]

by the way, where is the IAC? i havent tested my egr yet, but i found it today and it looks like it was replaced by the previous owner that i got it from bout 6months ago.

[dirtymuddog]

bout to test the egr tomm, but where's the iac? thanks again for yalls extensive help. if this stuff doesnt work im bout to take it to the mechanic, but the guy there that will be doin the work is my brotherinlaw, hes been doin guess work right beside me..starting with the everday problems. the main problem is that this is a jeep,they have a whole differant set of everyday problems than other vehicles.

[langer1]

the main problem is that this is a jeep,they have a whole different set of everyday problems than other vehicles.

By just reading this site you would think so because thats all we discuss but the problems are the same for all cars.
This is close to yours A is the IAC
http://img.photobucket.com/albums/v11/langer1/jeep/FSM/HO-Mana.jpg

[dirtymuddog]

i appriciate that...youve been alot of help man..yall get the best diagrams, i just have the ole crappy haynes manual, gotta order the chiltons

[dirtymuddog]

well time to go outside and see bout that egr....

[dirtymuddog]

i cant get the freggin new vaccum hose of the egr..havent gotten to the iac yet...im bout to just take it to the shop..damnit

[dirtymuddog]

could the iac keep the jeep from starting?