please help my jeep wont run, but starts then dies

[tonexj]

alright im having the hardest time tracking this one down!
let me list what ive done

replaced coil with a junkyard good looking one
replaced cps with a junkyard great looking one
replaced iac with two junkyard ones trying both
replaced tps with two junkyard ones trying both

bought the 93' xj 4.0L with a bad distributor it had the gears stripped off it but the oil pump turned okay and the camshaft gear looked good so i replaced the distributor with a BRAND NEW ONE.

now my jeep, will start if i hold the gas open above 1000 rpm. itll keep running, until i bring it down past 1000 and it stumbles and dies.

also during this process it was running very chunky every other time i tried to start it, like a horrible miss and a weird warm smell coming from exhaust as if missing.

so right now i was just out there trying to get it started and without any pedal pressure it will crank, start idle normal for between 2-5 seconds, then stumble and die.

i have no idea what the hell is wrong. the reason i got a different coil was because i checked the spark coming from the coil and it seemed very weak, didnt check the spark with the different coil because i just got frustrated that it didnt fix it,

ANY and ALL opinions or advice would be greatly appreciated!!!

 

[ROKTOYXJ]

Mine was doing this and I found in the fuel pump in the tank the rubber line was very deteriorated and would idle a few seconds and die. And if I hit the gas it would die altogether.

 

[tonexj]

yes i have that problem. but if i hold the gas from before i start it to until it idles, it will idle and rev up fine but then once it drops too low it does not

 

[SINCITY192]

DONT get fustrated keep testing and posting results here thats how you narrow it down
this might be a dumb question but does the 93 have a ballast resister for the pump

 

[zion14]

I would definitely check the fuel pressure. This sounds more like a fuel delivery issue than a sensor. I am not sure exactly what the psi should be but I read it on here last night. So a quick search could get you the right number. Good luck.

 

[tonexj]

i dont know, fuel pump turns on, and i hear it, and i get fuel pressure at rail, but i am unsure about ballast

 

[tonexj]

just checked the ballast used a jumper wire, it ran chunky again like it was missing and would die below 1000 rpm. no difference.

 

[SINCITY192]

make sure the connection is good and tight while its running and give it a second
i used cottor pins to jump my resistor at first i didnt think it was my resistor either until i had it crimped on the cottor pin on both sides and it ran good running direst after it relearn itself

 

[lorax81]

you say you have press what is the press you have should b 31 psi with vac hooked up 40 when not

 

[jth877]

MAP sensor?

 

[ParadiseXJ]

ANY and ALL opinions or advice would be greatly appreciated!!!

OK then.

Distributor: Is it possible (anything's possible) that the distributor was installed a tooth or two off? 180 degrees off?


Fuel delivery: Can you pull the fuel filter and see if you're getting any little chunks of rubber...or...change the filter? Fuel pressure regulator have good vacuum?

Spark: Is the battery strong enough, charged. Sounds like you've done alot of cranking without much running, or at least long charging running. Has it been charged and load tested? Did you replace the ICM or just the coils themselves? How are all your grounds?

Vacuum: Are ALL your vac lines where they should be? MAP? MAT?

Sensors: Sounds like you covered that but I never heard mention of any NEW stuff except for the distributor. Although I'm not a huge fan of just throwing parts at problems, sometimes a new part DOES do the trick.

 

[djc212007]

YEA it could be the vac lines to the map, mine ran like hell when i was diagnosing an idle issue. def. really look into that ballast resistor i hit the wire with my hand changing the air filter and it did the same thing i fixed it and it ran great after about a minute or 2 too relearn itself. other than that check the timing even 4 degrees will throw it out bad, trust me i know. lol good luck

 

[tonexj]

check the timing? how can it be out of the right tooth if it runs fine if i gas it past 1000 rpm? it doesnt miss at all?

 

[djc212007]

ooo, thought it was bad there to sorry, im stumped too then. sorry bud

 

[djc212007]

maybe just check it to be sure though.

 

[birchlakeXJ]

I would definitely check the fuel pressure. This sounds more like a fuel delivery issue than a sensor. I am not sure exactly what the psi should be but I read it on here last night. So a quick search could get you the right number. Good luck.

I agree. Check fuel pressure with a gauge. They can be rented from many parts stores.

You need to adopt a methodical, testing strategy to determine root cause.

No substitute for good solid data.

 

[tonexj]

checked my fuel pressure, its 31 at idle and spikes to 40 when u unhook the regulator, itll still put out and wont restart after about a half hour of running though.

 

[joe_peters]

Dying out after 30 minutes of running could indicate a thermal failure on the CPS/CKP crank sensor.

Take an ohm meter and TEST the CPS/CKP. Resistance should be 200 ohms, plus or minus 75 ohms, or 125~275 ohms.