hey everyone i have a 87 xj 4.0l my first jeep!! im 20 yrs old love to go off road. i have a few friends with lift Toyota's got tired of riding shotgun and wanted to behind the wheel. finally decide to get a wheeler it has a 4 1/2 inch lift and 32inch bfgoodrich At's on it.

i been trying to get it running for a few weeks now. it starts runs , once it warms up shuts off like it loses all power. it starts back up runs for a little same thing starts to happen. sometimes i can keep it from stalling if i rev it up.

my first step was to double check the wiring on the steering column.the reason behind that is the owner before replaced the turn signal switch. all of the wiring looks good.

my next step was to check the coil a friend of mine had a similar problem with his car. took it off bench tested it coil it was out of spec got a new one installed it nothing same problem .

i know the cps is a common problem on the jeeps the owner before me had it replaced. i double checked the wiring everything is in spec.

im running out of ideas on what to test and don't want to be one of those ppl who just throw parts at it until it something works

i work as a tech i have a good back ground in repairing vehicles

at this point i just don't know where to start again

i was hoping it was the coil since it was out of spec but i know better i have replaced parts before that where not working rite and still have the same problem

so i just need some input on what else to check or any ideas on what it could be.

i work Mon - Saturday i have Tuesdays off i been messing with it on my day offs for the past two weeks well really only two days but u know what i mean

thanks for any help
mike

 

maybe the fuel pump ballast is bad? i had a suggestion to fix that on my 88 but was out of time and money to try it so never got around to it.

Is the cps adjusted to the right ohms? i had replaced mine but mine wasn't completely tuned so it ran slightly funny until i fixed this.

 

Fuel pump ballast resistor may be giving up.. It may also be your fuel pump going out. I would get a fuel pressure gauge and hook it up, let the engine run until it dies, and check what the fuel pressure is at...

 

thank you guys for the very quick reply's

where would the fuel pump ballast located

and does anyone know what the fuel pressure should be around ?

also how would i adjusted the cps ?

thanks alot guys hopefully i could get this thing running and enjoy it

 

http://www.lunghd.com/Tech_Articles/...iagnostics.htm

 

good site

so im guessing my 87 is a renix engine ? what would be the difference between that and the 4.0L high output ?


thanks

mike

 

Renix is the computer control system, it was built by Renault/bENdIX hence Renix..

It is non OBD, therefore no CELs or codes thrown. It is a very simple system and can be tested with a multimeter.
The engine itself produces about 13 less horsepower, due to EGR and a slightly different cam grind than the HO engines. But many people claim they feel an increase in torque between Renix and HO cherokees..
After chrysler bought AMC they went to the HO engines, and a chrysler control system (started in 91)

 

nice got some history on my jeep now thanks alot

well at least i will know how to use my dmm alot better now lol

im always into learning some new stuff


thanks

mike

 

I dont know about a renix motor, but my 1991 ho had a similar problem and it was the engine temp sensor. The computer on some of the earlier injection systems are very dependant on that sensor. Mine would run fine and then just go all crazy and die. I didnt figure it out till one day I just accidentaly bumped the wire to it and it died. Hope that helps.
Brendan

 

this happened to my RENIX jeep twice. the first time i replaced the fuel pump and the balast resistor. i did it again about a year later and i replaced the resistor again, and it worked fine. the resistor is on the drivers side inside the engine bay by the air filter box, it should be white with one screw holding it in and two wires coming from it. cost ten bucks at napa and takes 5 minutes to replace.

 

thanks for the help is there any way i can test the balast resistor?

so i got a nice list of stuff to check and test and go from there

thanks to everyone who helped me so far

this forum is a great one !!!!


mike

 

im sure theres a way to check the voltage coming from it, honestly i wouldnt even bother its a cheap part and very easy to replace. twenty bucks says thats your problem

 

alot of people just splice the wires from teh ballast resistor together. They say it is only there to keep the fuel pump quiet (lower amperage..). I spliced mine together and didnt notice a difference in noise..

 

thanks for all the help guys hopefully i will have sometime this week to check the fuel pressure and what is when the engine dies.

going to swap out the ballast because it is so cheap hopefully that's all i need to do lol

thanks again guys i will keep u posted on how it goes


mike