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Cranks, but doesnt start...

pyrotyro

NAXJA Forum User
Location
CO
my jeep died (in a very inconvenient spot too, whole other story!) in a bad spot... it was idling when i got back in, and the check gauges and check engine light was on, my oil pressure gauge said 0. so i shut it off, after giving it some gas praying it would shoot the oil pressure up.

first off, yes it does have oil. it wasnt knocking, running hot or abnormally at all. after checking it out for awhile, i tried to restart it, but it doesnt. it cranks and cranks, but just doesnt catch. its disturbing because it WAS running, so i think it has spark (01, hard to check in the field), has fuel (hear the fuel pump, and get spray up on the rail).

all this leads me to believe somewhere something electrical is wrong. i read alot about the cps and the oil sender unit needing replaced alot, which would explain either of my problems separately (not having oil pressure on the gauge, and not starting because of something electrical). i did replace the CPS today (before we winched it out 2 miles, again another story) but no luck. havent tried the oil pressure sender, but technically that shouldnt stop it from starting.

so right now i have 2 (main) theories.
1) computer is fawked up. and switches off the ASD (automatic shutdown relay) and doesnt allow the rail to send a spark.
2) oil pump (or something related) is dead, and the computer is doing its job of not letting me burn it up!

thoughts, suggestions, miracles. all welcome!!
 
The first thing you need to do is actually verify if your getting spark from: the coil, and/or the plugs, thinking u have spark because in the field is not accurate.

have someone crank engine while first checking if their is an arc from the coil wire to ground, and not, then check the plug wires, at least 3 or four of them because i dont know how many the jeep needs to actually run. do NOT hold to close to the tip of any plug ends or we wont hear from you again!
try disconnecting the battery, hold down brake pedal for a min then try starting again. it might reset computer, sh!t it works on my Mx6GT

when my oil sending unit failed, it alwasy read pressure near or at the redline, barely ever moved, replaced it for a few bucks and now its accurate. you do not need oil pressure to start an engine, but oh ya it helps.
btw; what year is your jeep and what engine??
sounds like from what your not disclosing, u either know u fukd up something and not saying what u were doing at least not right now or fukd up something and have no idea!

If u had to get winched out, did u ford water? if so try draining a half to a full quart oil and check for water. did u replace the ckp on bellhousing, or the cps in dissy?? they are sometimes labeled the same.
you may have snapped the timing chain and it is not rotating the oil pump, nor allowing spark. if so. and you need to check, if memory serves, remove the cap and rotate engine, if the rotor doesnt move.... your chain is fukd. dont quot me on that, the gurus can verify, but a long time ago when i first bought my xj it had a no start no spark cond. I was told to check this... end up it was fine and the ckp was the issue.

ohh get ohm values from new ckps you installed. u never know it may be bad. . .

my 2¢ hope it helps
 
The first thing you need to do is actually verify if your getting spark from: the coil, and/or the plugs, thinking u have spark because in the field is not accurate.

have someone crank engine while first checking if their is an arc from the coil wire to ground, and not, then check the plug wires, at least 3 or four of them because i dont know how many the jeep needs to actually run. do NOT hold to close to the tip of any plug ends or we wont hear from you again!
try disconnecting the battery, hold down brake pedal for a min then try starting again. it might reset computer, sh!t it works on my Mx6GT

when my oil sending unit failed, it alwasy read pressure near or at the redline, barely ever moved, replaced it for a few bucks and now its accurate. you do not need oil pressure to start an engine, but oh ya it helps.
btw; what year is your jeep and what engine??
sounds like from what your not disclosing, u either know u fukd up something and not saying what u were doing at least not right now or fukd up something and have no idea!

If u had to get winched out, did u ford water? if so try draining a half to a full quart oil and check for water. did u replace the ckp on bellhousing, or the cps in dissy?? they are sometimes labeled the same.
you may have snapped the timing chain and it is not rotating the oil pump, nor allowing spark. if so. and you need to check, if memory serves, remove the cap and rotate engine, if the rotor doesnt move.... your chain is fukd. dont quot me on that, the gurus can verify, but a long time ago when i first bought my xj it had a no start no spark cond. I was told to check this... end up it was fine and the ckp was the issue.

ohh get ohm values from new ckps you installed. u never know it may be bad. . .

my 2¢ hope it helps

first about the spark plug, is on the '00 and '01 there is a distributorless system, which ya, makes it very difficult to test. i assume i have spark because i was running fine until i turned it off.

im pretty damn sure i didnt mess anything up, wasnt beating on it, no mud, little water crossing. and this vehicle has been running great for the past few months since i bought it, so it makes it harder to think there is something really wrong with it. but i cant rule that out yet, so thats why im thinking oil pump

oil sending unit could describe the check gauges and 0 oil pressure, but could that tell the computer to not let the engine run?

it seems like a complications of problems to me
 
well i have a 90 and a 94 xj, if your jeep doesnt have a dissy, does it still have spark plugs? if so remove them and lay them on a flat piece of wood or right near an engine ground. check for sparks, use the first hood prop hole so you can shade them better.

you are assuming the ignition is sparking. i understand your situation, however i have had to spend / waste a lot of money on assumption. you know they say assumptions are the mother of all fukups!
try and borrow a code scanner and see if it can read codes or if it maybe displays ignition information.

about the computer not allowing the engine to turn over if fault in oil pump/sending unit... i dont know; however if that was the case by all means it should throw a cel

try starting in neutral or other gears. . . for some reason the NSS gets very dirty. same problems as what a faulty ckp would do.
can you get the Ohm reading on the ckp you just installed?
 
well we finally found the problem! sure enough the distributor doesn't spin when we crank on 'er. i am really glad to finally be closing in on the problem. i hear these things are kinda a pain to replace? could there be a chance my pump is dead too?
 
more than likely the oil pump, is fine. like i said its the chain that let loose. it will be up to you while your in there to replace the pump. also drain your oil over a big magnet and see if any shavings come out.
 
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