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Cranks but won't fire, Neutral safety switch?

A

Atom

NAXJA Forum User
Location
Colorado Springs
Ok this is what I got… Jeep started dieing on me for no reason and then twenty minutes latter it would start right back up and then go for a few days. Now its in my garage and wont start at all. It cranks but wont start. I put a CPS in it as some people posted. Still wont start, so I put in a fuel pump. The fuel pump sucks too b.t.w.! Still won’t start! I then checked for fuel pressure with a fuel pressure gauge and its pressure is good. Next I checked for spark and no spark at the wires. I checked for spark at the coil and no spark there either. So next I bought a new coil. Still won’t start! I checked the leads going into the coil and they are at 10-11.5 volts?
I have spent over $250 and the Jeep is still not running!
The only other thing I can think of is the Neutral safety switch. It has been sticking some times and I have to work the shifter to get it to start. But then it would not even turn over, and now it does. Could this be the problem???
If not, WHAT NEXT?
 
It isn't the Neutral safety switch. The NSS controls the starter only, not the ignition, so if it cranks at all, the problem must be somewhere else.

Not sure how this differs with years, but my stepson's 93 had a no-start condition when the cam position sensor, which is inside the distributor, went bad. In this case, because it was a 93 that throws codes, the computer identified it. If yours is a pre-91, it won't give you a code, but it might be worth looking into.
 
No spark is normally indicative of a bad CPS. You said you swapped the CPS, so the next thing to do is to unplug the computer and then replug it back in. A bad contact on the computer can cause this as well.

Other possibilites that cause no spark are Cam Position sensor, like the man said, or a bad coil/ignition module. I've seen a lot more coils than Cam Position Sensors. If you have an early XJ, there is a connector called C101 that is mounted on the firewall above the brake booster. It is notorious for getting flakey. If you have it, plug and unplug it a few times. Do the cheap stuff first.

Rather than spending big money on a coil and Cam Position Sensor, go to a pull n save and scrounge them both. They are normally readily available. That way if they don't fix your problem, no big damage and you have trail spares.
 
I forgot to mention that when the cam sensor on the 93 went, it prevented the computer from going through its normal boot-up cycle. While working on it, I discovered that if I unplugged and replugged it with the ignition ON, the normal startup hums and buzzes would occur, and the engine would start and run, but wouldn't restart unless I did it each time. I'm guessing that this trick wouldn't work on a Renix (pre-91) model, but might be worth trying.
 
The jeep is a 1996 4.0- for those whom wanted to know.

Has anyone ever bought a new coil and or CPS that did not work? (B.T.W. I have replaced both and it did not fix it- trail spairs right?)

Does anyone know anything else that could cause no spark?

1. Crankshaft postition sensor is new
2. Coil is new
3. New ignition (forgot to mention that in my first post)

And thanks to all for the Unpluging and pluging back in the computer and Cam position sensor ideas, because thats really what I have to look at next.

Any other ideas???
 
On a 1991-1997 you can get the codes out of a computer by cycling the key three times and then watching the check engine light flashes. Mine has no trouble codes in it at all so that wont help.
BUT, I did have a trouble code about a month ago and I dont know if it could be invloved in this problem. It was for the Idle Air Control Circuit????
The code only came up once and I have not seen it again?
 
10-11.5 volts is normal, for the coil, at normal run. During cranking the starter sucks the system down to around 9-10 volts so the ignition system is feed more voltage, during starts to compensate.
Common causes for no spark are no pulse to the ECU, either CPS, wiring or as mentioned the cam position sensor.
During start (cranking) many engine controls, fuel, spark and others are switched over to a parallel system, often by relays.
Often overlooked are connectors and wiring. And less often fuses and relays.
If I remember correctly feed voltage for the CPS, is 8 volts and resistance is 5 ohms.
I can retrieve the stored codes from the computer in my 96 by, turning the key on and off three times (rather quickly). Number 11, is no reference signal detected during engine cranking. Code 12, battery disconnected in last fifty cycles and 55 completion of diagnostic trouble code display, often also pop up.
 
I am in the same boat right now. I also have a 96 and it wont start either. I was told it was the crankshaft position sensor. But I haven't had time to replace it. But now I wonder if I may have bigger problems after reading here. I just put on a new cap and rotor. I also unplugged the ECU and the CPS. Nothing. I even pulled and checked the Iginition coil, it too was fine. Let me know what you find out.
 
A few months ago my sister's '92 Briarwoody had starting problems that we thought was the starter or the not really funtioning aftermarket alarm (it was on the truck when she bought it), but it turned out al dad had to do was clean up the battery terminals and it has since started just fine!?
 
Thanks for all the info!
I did check all the relays and the fuses and they are fine.
I will check the wiring next and I have a good book to go through and check all of the sensors.
ONE NEW THING- When I turn on the key the electric fan runs??? I don't remember it working like that in the past. Any Ideas about this? Is it normal for it to run even before the car is running???
I will keep every one posted- I am planning on working on it tonight and all day friday, sat, sunday,....
Thanks again!
 
Atom said:
Thanks for all the info!
I did check all the relays and the fuses and they are fine.
I will check the wiring next and I have a good book to go through and check all of the sensors.
ONE NEW THING- When I turn on the key the electric fan runs??? I don't remember it working like that in the past. Any Ideas about this? Is it normal for it to run even before the car is running???
I will keep every one posted- I am planning on working on it tonight and all day friday, sat, sunday,....
Thanks again!
Click to expand...

It's not normal as far as I know, but make sure that the A/c or defrost isn't on. Sounds as if you need to look for wiring faults, perhaps a bad ground to the engine, or a shorted harness somewhere.
 
Just recollecting something I heard in passing. There is a relay out of the normal underhood relay box, near the coolant bottle, that has caused some people fits. Would probably take awhile with a wiring diagram, to figure out if this is relavent to your problem or not, but it´s worth a look. Pull it out, bang it a couple of times, maybe try swapping a relay from another, non critical spot, for a test. I might be just blowing exhaust gases, but heck it´s a five minute check.
 
Atom said:
Ok this is what I got… Jeep started dieing on me for no reason and then twenty minutes latter it would start right back up and then go for a few days. Now its in my garage and wont start at all. It cranks but wont start. I put a CPS in it as some people posted. Still wont start, so I put in a fuel pump. The fuel pump sucks too b.t.w.! Still won’t start! I then checked for fuel pressure with a fuel pressure gauge and its pressure is good. Next I checked for spark and no spark at the wires. I checked for spark at the coil and no spark there either. So next I bought a new coil. Still won’t start! I checked the leads going into the coil and they are at 10-11.5 volts?
I have spent over $250 and the Jeep is still not running!
The only other thing I can think of is the Neutral safety switch. It has been sticking some times and I have to work the shifter to get it to start. But then it would not even turn over, and now it does. Could this be the problem???
If not, WHAT NEXT?
Click to expand...


CAN YOU HEAR THE FUEL PUMP CLICK WHEN YOU TURN KEY ON, IN THE POWER DISTRIBUTION BOX RIGHT BEHIND BATTERY THERE IS A ASD RELAY,IT CONTROLS SPARK AND FUEL CIRCUIT. TURN THE LID OVER ON POWER BOX IT TELLS WHAT EACH RELAY IS FOR AND FUSES, ALSO CHECK THE FUSES. BADGE714 [email protected]
 
Fuel pump is pumping- the fuel rail has up to 50psi of pressure and it builds back up when all the pressure is released. I check the fuses by swapping them all out one by one. All the relays work too, checked them by swapping them too... I am just checking all the sensors one by one with the book to see if I can find one testing wrong... Thanks for the info, Atom
 
Atom said:
Fuel pump is pumping- the fuel rail has up to 50psi of pressure and it builds back up when all the pressure is released. I check the fuses by swapping them all out one by one. All the relays work too, checked them by swapping them too... I am just checking all the sensors one by one with the book to see if I can find one testing wrong... Thanks for the info, Atom
Click to expand...

DID YOU CHECK THE ASD RELAY IT SHOULD HAVE 12 VOLTS ALL THE TIME ON ONE OF THE TERMINALS BADGE714 [email protected]
 
Went out to work on it tonight and it has spark from coil. I connected it to the distribitor and the jeep started right up???????
I guess I will drive it until it happens again what else can I do?
Could the computer have reset its self after I let it set for about 48 hours?
I did nothing to it, the coil had no spark on Tuesday after noon and today, Thursday it runs?
Any ideas?
 
Atom said:
Ok this is what I got… Jeep started dieing on me for no reason and then twenty minutes latter it would start right back up and then go for a few days. Now its in my garage and wont start at all. It cranks but wont start. I put a CPS in it as some people posted. Still wont start, so I put in a fuel pump. The fuel pump sucks too b.t.w.! Still won’t start! I then checked for fuel pressure with a fuel pressure gauge and its pressure is good. Next I checked for spark and no spark at the wires. I checked for spark at the coil and no spark there either. So next I bought a new coil. Still won’t start! I checked the leads going into the coil and they are at 10-11.5 volts?
I have spent over $250 and the Jeep is still not running!
The only other thing I can think of is the Neutral safety switch. It has been sticking some times and I have to work the shifter to get it to start. But then it would not even turn over, and now it does. Could this be the problem???
If not, WHAT NEXT?
Click to expand...

OK later on you state it's a 96 and I have a 96. Behind the distributor bolted to the engine block are 4 or so ground wires. I read they are the ground points for various sensors. Mine were pretty shabby and that's a place to look at. Also the only cost is time.
 
My 96 had similar troubles for about a year, replacing the cam position sensor in the distributor fixed the problem, I went through everything else everyone has mentioned here, but that is what fixed it. It is definitely a "now ya see it now ya dont" type problem, ultimately I got lucky and worked with someone who had seen it before.
 
Can't tell from the postings whether you got it fixed yet, so here goes:

I had a similar problem with my '95. A varity of symptoms that were different from time to time and intermittant (worse kind of problem). Sometimes it just wouldn't start. Sometimes it would start but the starter would grind when in park or neutral. Usually, the heater and radio would not work when the problem occured. Initially the symptoms would go away after a few minutes and it would run fine for several weeks. Finally, last week, it began showing all the symptoms and nearly left me stranded at one point.

Found the ignition swith (that part attached to the key cylinder inside the steering column cover) had at least one short and a burnt wire in it. Fairly easy replacement job. Starts normal now and all accessories work normal as well.

Hope this helps.

redxjjoe
 
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