Panama XJ
NAXJA Forum User
- Location
- Panama, Central America
Check for a crack in the fuel regulator diafragm it can leak lots of fuel to the intake manifold
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90 xj nightmare please help
- Thread starter 90xjpos
- Start date
BruteXJ
NAXJA Forum User
- Location
- Charlottesville, VA
Is Eagle on vacation?
live24wheel
NAXJA Forum User
- Location
- Phoenix
Mine had the EXACT same problem as yours and we thought it was the cps so they put a new one in under warranty on my 90' because i had just had it replaced a few months prior. Turned out it was the ignition module and the coil. the module fixed the problem and the coil made it stop running rough. I would look at the module.
Tom
Tom
if i remember my start sequence correctly for the renix era...
when the engine turns over... you turn the engine switch to acc... it pressurizes the fuel system at full voltage.. the engine turns over when you turn it to start, and the injectors fire... once enough revolutons are done to get the oil circulated, the renix box lets the ign. control module (that heat sink under the coil) fire the engine and caboom we have combustion... the fuel pump continues to run the entire time the engine is running only at a reduced voltage via the ballast resister on the left fender wall.... i had a huge problem with a short in that wire on mine... orange wire brown tracer if i remember it was a nightmare that seriously involved prayers and ghosts and the same things you had.. see my other post
when the engine turns over... you turn the engine switch to acc... it pressurizes the fuel system at full voltage.. the engine turns over when you turn it to start, and the injectors fire... once enough revolutons are done to get the oil circulated, the renix box lets the ign. control module (that heat sink under the coil) fire the engine and caboom we have combustion... the fuel pump continues to run the entire time the engine is running only at a reduced voltage via the ballast resister on the left fender wall.... i had a huge problem with a short in that wire on mine... orange wire brown tracer if i remember it was a nightmare that seriously involved prayers and ghosts and the same things you had.. see my other post
HossHoffer
NAXJA Forum User
- Location
- Aurora, CO
90xjpos said:
Yes, as a matter of fact that is how you tell that the diaphram is cracked. Check that out asap. There is a bleed down test for the fuel rail but I can't remember it offhand. That would let you know for certain. I'll try to find it and post if you need it.
Oldmanxj
NAXJA Member #940
- Location
- Loomis, Ca
Had a similar problem, pump kept running. The starter relay's contacts had fused. Its located buy the battery, silver and about 2" X 3". (thxs crash)
To check fuel pressure regulator, connect fuel pressure gauge to pressure fitting (on fuel rail). Start engine and pressure should be 31 psi, then pull vacuum line from regulator and it should go up to 39 psi. good luck.
To check fuel pressure regulator, connect fuel pressure gauge to pressure fitting (on fuel rail). Start engine and pressure should be 31 psi, then pull vacuum line from regulator and it should go up to 39 psi. good luck.
94XJ4x4
NAXJA Forum User
- Location
- Bitburg, Germany
HossHoffer said:
If the fuel pressure regulator has a crack in it and leaks enough fuel this could cause your fuel pump to run continuously because it never gets up to full pressure. I would think it would have to be leaking like a water fountain though. The rough idle and black smoke may be caused by this fuel leaking into the intake manifold. The fuel would be drawn in with the incoming air and confuse the hell out of the computer. Then if the engine backfired it could cause the flame that ignited the air filter and created the black smoke. Ive never done a leak down test on my xj. Only one on a sunfire in tech class last year. As i remember you will need a fuel pressure indicator/guage. There is a little valve stem looking deal on your fuel raild. attach it to that. then pressureize the system by tunring the ingnition switch to the run position or starting the engine. shut the engine down or switch the ignition to off and watch the guage to see if it drops. It shouldnt drop and if it does you have a leak somewhere. good luck.
-Tim
old_man
NAXJA Forum User
- Location
- Loveland, Colorado
If the fuel pump keeps running, there are only two things that can be causing it. Either the pressure switch on the fuel pump is bad or the fuel pressure regulator on the fuel rail is bad. Most likely is the fuel pressure regulator. They can be pricey, so hit a pull and save to snag one. The don't tend to go bad very often. If nothing else, hit the wanted section on this forum, I bet someone will have one they will part with.
latest update. well for one when it starts now it dont stop. i am sure you have all read the post on that by now. and second. when i pull the plug on the ballist for the fule pump the darn thing kept on pumping still . so i crawled under and pulled the plug that is about 3 feet back from the fuel pump and then it shut off. thinking maybe a short in the key cylinder switch in the colum would anybody else jump on that band wagon with me. or am i way off?
Okay the chart is in front of me
fuel pump has two wires going into it .. black wire goes str8 to gorund and orange wire has feed
feed comes from Three soruces... source one is orange and black wire on starter relay (right by your battery) hey that could be stuck
disconnect the orange and black wire from that relay see if that kills it
source two is off the ballast resister... that aint it since disconnecting it doenst work
and source 3 is
a black and orange wire that
goes to the bottem of the o2 sensor relay pop your o2 sensor heater relay out.. its on pole 87 of the relay why its there i dont know but htas the setup...
the o2 sensor relay is going to be one of 4 relays behind the battery
one is latch relay
one is air cond
one is o2 sensor
one is fuel pump
the fuel pump relay goes to the ballast ressisstor b4 heading to the pump
so whatcha got to do next is 1st id pull the orange and black wire off the ballast resisistor (its not going to die we already tried that)
now leaving that off... i would yank the wire from the starter relay (orange and black)
if she dies... well you got a bad starter relay thats allowing power the entire time
VERY LIKELY YOUR PROBLEM
if she doesnt die and you yank the o2 sensor relay and she does... well you got a bad o2 sensor relay and you can temp swap oyu the ac relay
right now i am betting that its going to be your starter relay
not your ignitoin swithc
fuel pump has two wires going into it .. black wire goes str8 to gorund and orange wire has feed
feed comes from Three soruces... source one is orange and black wire on starter relay (right by your battery) hey that could be stuck
disconnect the orange and black wire from that relay see if that kills it
source two is off the ballast resister... that aint it since disconnecting it doenst work
and source 3 is
a black and orange wire that
goes to the bottem of the o2 sensor relay pop your o2 sensor heater relay out.. its on pole 87 of the relay why its there i dont know but htas the setup...
the o2 sensor relay is going to be one of 4 relays behind the battery
one is latch relay
one is air cond
one is o2 sensor
one is fuel pump
the fuel pump relay goes to the ballast ressisstor b4 heading to the pump
so whatcha got to do next is 1st id pull the orange and black wire off the ballast resisistor (its not going to die we already tried that)
now leaving that off... i would yank the wire from the starter relay (orange and black)
if she dies... well you got a bad starter relay thats allowing power the entire time
VERY LIKELY YOUR PROBLEM
if she doesnt die and you yank the o2 sensor relay and she does... well you got a bad o2 sensor relay and you can temp swap oyu the ac relay
right now i am betting that its going to be your starter relay
not your ignitoin swithc
thanks for the great advise i will try that at the break of dawn. if you dont think its an ignition problem, then how do you explain the fact that the jeep dont shut off when i turn the key off and pull it out? thats what made me think it was that. and the buzzer for the fule pump prime dosnt stop untill the jeep starts. if it starts....... anyways i am sure you are off to bed already not everyone falls in the insomniac catagory such as i do. but i very greatly appeciate the help on the diagnostics i couldnt make heads or tails of that wiring diagram. the only darn thing i could figure out is that that black wire that it shows on the diagram pointing down is the ground. also that the guy who made the diagram was colorblind. because the fule guage wire isnt pink with white tracer. its as purple as that darn big goofy looking dinosaur. so anyways THANK YOU SO VERY MUCH. YOU HAVE BEEN THE GREATEST HELP YET. if your ever in hick country montana swing through a lil place called dillon. some of the greatest trails i have ever rode are within 40 minutes of here.
defenestrate
NAXJA Forum User
- Location
- central nc
your 90xj has a gm steering column AND lock cylinder/ignition switch. that's why you have two keys, probably a round looking one and a square looking one. what this means in practical terms is that the lock cylinder has all the quirks of the gm lock cylinders, like failing key retention on certain models. many gms will run if you pull the keys. they called it a "feature".
my guess i that either your ballast resistor is hosed or your ballast resistor bypass relay is hosed. if your fuel pump stays "running" that would tend to indicate otherwise, but it's just a thought. i'm not sure whether the relay can leave the vehicle trying to run without cutting down the voltage to the fuel pump, but that's what the ballast resistor circuit in an xj is for. i'm also thinking ignition switch. have run into these problems before as well as an early failing CPS (a CPS should last you 100K miles, so a 50K warranty isn't very impressive). jsut a thought.
my guess i that either your ballast resistor is hosed or your ballast resistor bypass relay is hosed. if your fuel pump stays "running" that would tend to indicate otherwise, but it's just a thought. i'm not sure whether the relay can leave the vehicle trying to run without cutting down the voltage to the fuel pump, but that's what the ballast resistor circuit in an xj is for. i'm also thinking ignition switch. have run into these problems before as well as an early failing CPS (a CPS should last you 100K miles, so a 50K warranty isn't very impressive). jsut a thought.
An update... i am thinking that its got to be the starter relay because thats one of 3 things that makes the fuel pump run, and i THINK the green wire off the starter relay also poweres the ignition... so i am thinking this is got to be it i am at work and dont have my wiring diagrams but i will check tonight... beleive me I have been where you were... even to the part with the rubber chicken and the moon lined with mars... i seriously had problems with mine and when i said a prayer the thing started working... its posssessed by an evil french demon
wilcharl your a friggen genious. i could so buy you a keg right now. ok so heres the deal. all the wires going into the starter relay are bolted in. its snowing like a s.o.b. here. and i got 4 harleys in the garage righ now so the jeep sits outside. so i didnt have the patientce to go digging to pull that bolt. but i saw were the oarange wire came out of that harness and pluged into something below the coil. i pulled the plug from the ballist. then started er up. pulled the oarange wire and viola the p.o.s. died . omg i friggen jumped for joy so loud and so much i think i woke the entire neighbourhood up thismorning. i called every place in town looking for a new one. car quest cant get them and neither could anybody else. but nobody answered the phone at napa so i went down there. they said they could have one here in 3-4 days so i ordered it. oh friggen happy day. my baby gets to go run the trails this weekend. this is going to be so much better than getting a piece of tail. i cant friggen wait. anyways thank all of you for your suggestions. i found alot of other things that would have caused trouble very soon because of them. but wilcharl your a god amongst gods'.
Look on the fender under the hood on the drivers side. You should see an off white ceramic thing-a-ma-bob with two wires plugged into it. This is a ceramic resistor. It is supposed to work with the fuel pump to keep it from running continuously.
Unplug the two plugs from the resistor and jumper between the plugs with a piece of wire. See if it helps.
Never mind.... :laugh3:
Unplug the two plugs from the resistor and jumper between the plugs with a piece of wire. See if it helps.
Never mind.... :laugh3:
ok so seeing as i had all day today with nothing to do but sit and wait for the starter relay . and the ignition switch was only 11.99. i decided to fill my day with replacing it. we'll just call it. one of those better make sure type things. now its preventitive maintanance. needless to say. it wasnt the starter switch. and i feel sorry for anyone who ever has to change one of those. took all day. what a mess. more in special tools than the part cost.
but it turns alot easier now. so i guess all thats left is the starter relay. and if that's not it i dont know were to go from there. any suggestions?
but it turns alot easier now. so i guess all thats left is the starter relay. and if that's not it i dont know were to go from there. any suggestions?
If the relay doesnt do it... and the more i study the wiring diagram the more it HAS to be it... the next step is to take a meter to the wiring harness and find any shorts in it.... it takes about an hour to do with a wiring diagram.. if the starter relay doesnt do the trick, let me know and I will email you the wiring diagram... I have a complete set of diagrams and maintance manuals for that year from my own cherokee saga...
