90 xj nightmare please help

ok so yesterday i bought a 1990 cherokee limited 4.0. took it for a test drive everything worked fine. went and got it titled and liscenced. it started fine like 6 times. went home. i left to go put gas in it. started fine when i left. got to the gas station. filled it up. and whamo. no start. it just kept turning and turning. finaly after like 15 minutes of all that. it starts. i was like YIKES!!! so i took it to the local auto shop. they spent all night working on it. new plugs tested the fule pump new fule filter new coil. new cap , plug wires, still couldnt get it to start again. it then came closing time and i had to leave my new baby there. so i came home and got on the net and fond this forum. found that alot of the time the problem was the CPS. sure as shit first thing thismorning i went and got a new one . and it started right up. got it home. and shut it off. .then again i go to start it. and nothing. just kept turning and turning and turning. so i wiggled the wire to the cps and it started. i went under the jeep and tightened the blots and still nothing then all of a sudden it started. so i left it running to recharge the battery from being turned so many times. after about 2 minutes it died. i went out and turned and turned and nothing for the first few times. then finaly it started. i was like "huh wonder what the problem could be" so i shut it off and started it again it started fine. then all of a sudden there was smoke. the air filter cought fire. i shut the jeep off. the fire went out on its own. instantly. took the filter out and started it again. and there was smoke comming into the filter housing from the intake tube. shut it off let it sit for like 15 minutes. went to start it again and it wouldnt start when i stopped turning the key. i hear alot of noise like engine noise. and smoke came belllowing out the air cleaner box. if anyone is reading this. PLEASE HELP. I HAVE BEEN SAVING FOR A JEEP FOR A LONG TIME. I HAVE ALWAYS LOVED THE 90 LIMITED. AND NOW MY BABY IS DEAD IN THE WATER. PLEASE HELP!!!!!!!!!!!!!!!!!

90xjpos; Welcome... You have my attention but that is all I can add. Rest assured someone will weigh in on this shortly. There are some very knowledgeable guys here.
I am as curious as you for the responses! Good Luck...

Hey, I can't help you much either, but I love the creativity of your username-- how did you get the idea? :laugh3:

csuxj said:

Hey, I can't help you much either, but I love the creativity of your username-- how did you get the idea? :laugh3:

Click to expand...

I'm sure that question was directed at 90xjpos, but an interesting truth about mine is:
one day I was typing "Idaho Jo" on a website as a user name and poked my finger between a couple keys and it just came out that way!

Hmmm, cant say I have ever seen an air filter catch fire :wierd: After you pulld the air cleaner, and started it again, how long did it smoke and what color was the smoke ??

Welcome to a renix era XJ worry not the system is a piece of cake.. wiggling the CPS and it working tells you its the CPS system

With all the woes its a very simple system.. All it is is 2 wires from the computer under your dash to the sensor... Depending on the year its seperated by one or two electrical connectores whcih can be a problem... Chrysler came out with a mod where you run wires directly to the computer from the CPS bypassing some of the connectors in route i THINK they were already incorprated into the 90 model year.. none the less... the CPS is real close to the exhaust manifold... its wires like to get melted ... what i would do is check that first... 2nd i would run new wire from the computer thru your firewall and directly to the CPS... 3rd if you bought the CPS from autozoo or advance its probley a POS CPS had 2 of them bad otu of the box.. its one part thats not that expenisve and should come from chrysler... if you plan on replacing the wiring go with one off an 87 or an 88 that comes with the direct to comptuer wiriing kit that comes with all new wire str8 up to the computer.. .The renix system is a big tedy bear and like anything french is ellegent but complicated.

I cant really help ya much, but was your air filter covered in oil???? Maybe you had some blow-by and hten it somehow caught fire? I dunno... ANyways, welcome to the forum, and to jeeps, I love my renix xj. Good luck.

Im thinking after i posted... the intake could have filled up with fuel from the lack of cranking i woudlnt worry though the xj is bulletproof i have had two major electrical fires replaced the entire harness that i hand redid my self not much u can do that you cant fix

from lack of cranking? or from over cranking. beleave me that thing was turned over more times thismorning a 6 months worth of starting. yes there was some oil in the air box but not much and the rest of the filter that was left had none on it. the filter was new. what would cause flames or smoke to come back out the intake? a buddy of mine said timing. but that dosnt seem to make sence to me because it was starting sometimes after i tightened the cps. and also i dont think the cps would be causing the flaming. it is a heavy duty cps. from an aftermarket company called bullet proof. the name speaks for its self. it has a 50,000 mile warantee on the thing. $89.00. i've got fule in the cylenders and i have spark on all 6. i tested it witht he plugs themselfs. believe me. i got good spark bright blue. i just cant figure out why the darn thing would spit smoke back out into the air box. and how come so much. i dont want to try and turn it over again untill i have a good idea what the problem is and have tried to remidy it already. oh . and the name. 90xjpos. it's self explanitory. i have been saving and searching for the right xj for a long time. and now i got one. and it's a piece of ****. and there is no jeep dealership within 120 miles of here. so that option is out. the only thing i can think of is timing. but it dosnt see, logical to me. if it was off that bad it wouldnt have started right before the fire.i have also checked the plug wire order and it is correct. again PLEASE HEALP ME!!!!!!!!!!111 MY BABY IS BEGGING FOR SOME MUD. BUT WONT GET IT UNLESS SHE RUNS....

I would say timing myself. I've seen things run with the timing off. that is the only thing in my mind that would allow something like that to happen.

I would tend to think that you are running extremely rich if you backfired bad enough to set the air filter on fire. You might try a new coolant temp sensor. Other than that you might have to run all the engine diagnostics and get back to us. Generally, hard to crank is one of the sensors. Crank pos., throttle pos, coolant temp.

Ok New Update. The Fule Pump Just Keeps Running. It Dosnt Shut Off Like It Should After A Few Seconds Of Priming. I Got The Balls To Start It Again And Holy Crap It Turned Right Over. After About 30 Seconds It Started To Idle Rough And I Could Smell Gas. When I Took The Rpm's Up It Ran Fine. Didnt Miss Or Anything. But Let It Idle Again And It Stutters And The Gas Smell Comes Back. I Put The Old Fule Pump Back In. And Same Problem. Is There A Switch That Signals That Darn Thing To Stop Pumping So Darn Hard And To Quit Priming?

Check the vacum line between the throttle body and the map sensor. Mine did the same thing and come to find out it was a $4 fix. Not too sure about the fuel pump issue.

yes sounds like the fuel pressure regulator.
forget the timing, its not adjustable, there is a tab molded into the distributor it stays in one spot and the advance retard is computer controlled.

Bad gas?

ok so how do i check the fule pressure regulator? if that is the problem can i just replace the regulator or should i just try and get one more new pump . i guess it wouldnt hurt if someone thinks it would work. that mud is calling my name. and i want to go play. and yes it did have bad gas. i smlled it before i bought it. so i used some sea foam. before we even started it the first time when i test drove it before i bought it. would that cause the fule pump to just run and run and run? also what can i expect to pay for a pressure regulator if that is the problem?

mine dumped mad fuel in when there was a bad ground to the chasis wait a minute i had all your symptoms from a bad ground... IT dumped fuel like mad fuel pump didnt stop running and the CPS went in and out.. Check your firewall ground and i would even add another one *its by injector six* and runs to the firewall run a piece of copper wire for the time beeing and see if that doesnt help ... bad grounds are renix night mares.. the fuel dumping cost me my cat on mine

Black smoke from the intake? the only time I got black smoke from the intake was when I blew a coonecting rod through the block. So that proves another point not all XJ's are bullet proof. The black smoke came from the rest of the connecting turning the bearing into shrapnel. then it started clanking around. When I pulled the valve cover plug is was like a chimeny. Thats my $.02.

i checked the ground and the vacume line. both fine. and pump keeps running. i know it is a problem with the pump as to why it flames every once in a while. it is flooding the motor out at low rpm's. I CANT GET THE DARN THING TO STOP RUNING LIKE THAT. WOULD IT MAYBE BE POSSIBLE TO PUT A MANUAL KILL SWITCH ON IT. SO I COULD LIKE SHUT IT OFF ONCE IT STARTS. SO IT DOSNT KEEP RUNNING LIKE IT IS PRIMING WHEN YOU TURN THE KEY BEFORE IT STARTS. SUGGESTIONS ANYONE. I JUST WANT TO GO PLAY IN THE MUD WITH THE REST OF THE BIG BAD JEEPS AROUND HERE.

The fuel pump is powered via the ballast resister which is located on the left fender by your air filter.. yank that wire and it kills the fuel pump... the deal is when u turn the ignition on it buzzes for a few seconds pressurizing the fuel system... when the engine starts the pump continues to supply postive pressure to the fuel rail when you kill the pump the engine will die within 3 seconds.. if its not an electrical problem whihc its starting to sound like its not i would do the fuel pressure regulator its a 5 minute swap and about 50 bucks.. autozoo and advance and all them carry it. spekain of fires under the hood an injector swap is a must on your year.. they will leak catch fire and no more jeep