Cranks, starts and dies immediately

O

Orodreth

NAXJA Forum User
Location
Greenville, SC
Long story:
So here I am driving my '90 XJ, and it dies out of nowhere with no apparent reason. It has 310k miles on it, so it's not an unusual thing for it to die unexpectedly for a second but it usually starts right back up.
It didn't this time, then the battery died. So I pushed it into a parking lot and got my friend to come pick me up and we tried to jump it and same issue. cranks but won't start.
The next day I tried to start it up again and same issue. Got it towed to my house and let it sit for a day or so and I tried to start it today and it started right up and then died after less than a second. It did this about three times.

Short story:
1990 XJ 310k miles
Dies unexpectedly while driving.
Wouldn't start up again just cranks.
Battery died.
Starts a couple of days later and dies immediately.

Halp?
 
you need fuel, air and spark

spray starter fluid in the throttle body and see if it will start and run

hold the throttle open to see if its lack of airflow

check for consistent spark by pulling a plug and laying the threaded body against a solid ground
 
The "ballast resistor" is suspect. A cream colored resistor somewhere on the fenderwell or firewall. Try jumpering that resistor. If that works, you can either replace the resistor or you can leave it jumpered. That resistor is only there to reduce noise on the fuel pump circuit; later models don't have this.
 
I haven't done a real try of the ballast resistor, I kind of did a half-assed attempt and it didn't work, so I'm not ruling it out.
I try to hit the gas every time it starts up, and it seems to rev, but it just quits immediately.
I'm going to do a real try with the ballast resistor or even just splicing those two cables together since I don't really have a good cable to use.
Thanks for the suggestions though.

I have a couple of other unrelated problems though:
1. None of the power windows work aside from the passenger. The driver window worked up until this past summer, but quit for no apparent reason... It's kind of a pain.
2. Kind of trivial; but the over-head computer stopped working. Sometimes it comes on with just a dash. I want to say it stopped working altogether around the same time as the driver window, but I'm sure it's an unrelated coincidence. (I say this because sometimes it'd say it was like 10 degrees during the summer. and it never said anything but the temp. and would just go blank when I pressed the 'step' button)
3. I'm also not getting any oil pressure on my oil pressure gauge. But I'm told that's a normal problem, and I just have to keep an eye on it. Not to mention the massive oil leak I have somewhere on the thing.

It has 310k miles... I think it might be time to garage it for a while.
 
I just checked my CPS, it should read 125-275 ohms across the connector and give you 1 to.5 A/C volts reading when cranking over. (Mine read 215 ohms, haven't tried the cranking over test yet.)
 
Still having this issue.

I have spark, gas, ballast resistor is bypassed, throttlebody has been taken off and cleaned thoroughly.
I'm going to replace the CPS tomorrow. though, I don't think that's the problem still because it wouldn't be starting at all, it'd just continuously turn. At least that's what happened last time I had to replace it. And that's what it does when I unplug it. I heard from someone that it could be the Ignition coil, any idea?
 
You mention having spark, but the "quality" of spark is also very important. You are looking for a strong, blue, snapping spark. Yellow/orange/white indicates a weak spark, which may not be strong enough to start the engine.

Ignition coil can be tested for primary and secondary resistances with a manual and a meter. Also for a 90, there is the "ignition control module", which is located directly under the coil.
 
Would that cause this particular problem though? Because its getting enough spark to start and run while the key is in start position (I am aware that doing that is bad for the starter) but dies as soon as I put it in the in position. I would think if I wast getting the righ spark that wouldn't be happening. But I admit my ignorance, I could be wrong.

Now would the ignition module be causing this problem?
 
A couple of thoughts:

1st - I would recommend checking your fuel pressure on the rail to ensure you are hitting at least 30lbs. It is an easy thing to check and this will ensure that you have the fuel part of the equation working properly. I had an issue with a loose hose in the tank and found that the beast ('90 XJ) wouldn't start until I built up at least 20lbs of pressure.

2nd - mine also had no reading on the oil pressure gauge. I found that the sensor (hanging below the oil filter) was "open" when I tested it with a meter. Bought a new one from O'Reilly's and it worked perfectly again.

3rd - the doors on the XJ are designed to route water, not stop it. Water will slide past the center window post and fall to the bottom of the door where they drain out of some small holes. As such, the inside of those doors is a pretty nasty environment. I found one of my window regulators filled with rust inside after it failed. Not much you can really do except hit the junkyard and pickup replacements.

HTH
Todd

Orodreth said:
Still having this issue.

I have spark, gas, ballast resistor is bypassed, throttlebody has been taken off and cleaned thoroughly.
I'm going to replace the CPS tomorrow. though, I don't think that's the problem still because it wouldn't be starting at all, it'd just continuously turn. At least that's what happened last time I had to replace it. And that's what it does when I unplug it. I heard from someone that it could be the Ignition coil, any idea?
Click to expand...
 
So this is what I've done today:

Replaced the CPS, replaced the ignition coil, fuel filter.
Cleaned the spark plugs.
Yesterday the throttle body was cleaned.

Still no change.

Thinking it's an ignition or computer problem, because nothing is changing anything ever in the world
 
What is the CPS cranking voltage? Where did you buy the new CPS? Did you customize the CPS mounting yet? (Move it closer the flexplate teeth)

Check the fuel pressure regulator vacuum line for gasoline, from a ruptured diaphragm. Check (CLEAN ALL, repeat ALL the ground contacts, battery, block near the oil dipstick, head to firewall ground wire contacts) the Grounds, it may be affecting sensor data (common on the Renix years, 87-90), thus affecting ECU timing.

If the IAC ( or the relay/timer that sets it om engine shut down), is not letting in enough air, try WOT, and then 10% throttle after it starts to see if it is a flooding problem from too little idle air, or too much idle fuel.
 
Do what ecomike suggests first.

I want to know the CPS output voltage. Should be .5 AC volts.

Another preventative thing to do and to eliminate potential problems is to unbolt the coil from the ICU, tweak the contacts tighter so they grab the pins better, clean any corrosion and bolt back together.
 
i know it sounds dumb lol but i went through a 2 day episode with my newly aquired winter dd

i have a 91 cherokee and went to start it up .,..... fired ran for 5 sec than stalled....hmmmmmmmmmmmm so i began traicing things like fuel spark air once in awhile it fire up by fluke turns out ign coil pack plug with the 2 wires to it had a snapped tab so it wasnt locking so cold startup engine shakes rattles connecter out just enough to stall it .....


long story short my issue is fixed check all connecters make sure each is locked with tab in place un plug connecter and re plug try again diagnose it

but thats my 2 cents as a newb to the forum
 
Never a bad idea to go through your engine bay with a can of electronics cleaner unplugging, visually inspecting, spraying out, and reconnecting every plug/connection you can find.
 
I haven't tested the cranking voltage. I bought the CPS at Autozone. I wasn't aware about the CPS mounting customization, is it simple to do?

I haven't checked the grounds yet. I've been needing to do that anyhow for a while now (I drive a bucket of oil pretty much.) So I'm going to try that tomorrow and check the voltage for the CPS. You guys have been a great help. Keep the suggestions coming please!
 
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