i bought my first xj back in feb of this year and ive spent alot of time getting this thing ready. while im driving it and i accelerate it does fine but when i pt it to the floor it bogs spit sputters and will stall. ive replaced fuel pump and filter, fuel line, distributor cap rotor wires and plugs. while looking at the motor we saw the map sensor was unhooked but when we hooked it up the jeep wont even idle. it runs really rich to. im supposed to take the jeep to uwharrie this thursday. any help would be great!

 

reset the PCM,

Unhook the positive battery cables and hold them to the Negative post for about 30 seconds.

make sure everything is hooked up properly, then start it and let it idle for about 3 minutes, then go drive it like normal and see if it is fine

 

ill try it tomorrow...a buddy thinks it might be an o2 sensor

 

Did u mess with the fuel rail at all or did the po? I've heard of similar symptoms from a nicked injector oring. Makes it run super rich an most people don't think about it. Just a suggestion can't hurt to look if the reset doesn't work.

 

well nobody makes the fuel line clips any more so i just ran a fuel line hose to the rail

 

the Factory still stocks all of the fuel parts...

if it is not how it was when it was factory installed and it is now installed differently then that may be an issue to look into as well.

and x2 on the o-rings getting nicked.

have you done a fuel system test? both at idle and while driving?

 

i know its getting fuel because it runs so rich it will burn yours eyes if your around it for a lil bit

 

the reason I bring up the Pressure test is if you are getting way to much pressure then you have a bad pressure regulator and that could be the source of your problems.


electronics to look into:
MAP
TPS
IAC

 

You say the MAP sensor is UNPLUGGed and that when you hook it up the motor dies? I would suggest you start with the KNOWN bad map sensor. If its running rich the O2 sensor will be toast. Fix those items first. Pull the codes from the computer, before you reset it, be better if you don't reset it till you fix the known issues.

 

if the map sensor is unplugged for long enough the computer will relearn not to use it. which is why you have to reset the computer to make it relearn to use it again.

Heck my jeep I can unplug mine and it will run almost perfect, a little rich and it died twice but didnt notice a difference.

the map only controls so much fuel anyways, then the TPS takes over.

 

well im gonna put an o2 sensor in tonight and clean the throttle bodybut puttin the battery cables on backwards dosent sound like a good idea to me to reset the computer.

 

also the jeep isnt throwing codes. i guess i should mention its an 88

 

well reset the computer and the thing wont hardly run at all now. it seems like its getting to much fuel and then we turn around a bleed the fuel rail and all it does it spit out air. theres no fuel in the return line either

 

The reset didn't work and your not throwing codes because youre "Computer" isn't that smart. Welcome to the world of Renix my son.

Have you pressure tested the rail yet??

 

THIS.

The first thing a shop would do is to verify fuel pressure. If you have a ruptured fuel pressure regulator (no mention of replacing this), you can have the exact symptoms you describe.

For an 88, you should have 31 psi at idle. Then when the vacuum line to the fuel pressure is disconnected, the pressure should jump to 39 psi.

Test your way to a solution......I wouldn't throw any more parts at it.