Have gas and spark but will not fire???

[nate438]

Tried it 3 times and it actually acted like it wanted to start but them my battery got to low. I'm letting it charge over night and will try it again tomorrow and let you know if how it goes....

yes I have spark, and no somone did not try to make french fries out of my tail pipe

 

[nate438]

Ok the battery was fully charged and I tried the oil trick 2 more times and nothing. Getting very frustrated here so I talked to the shop once more and now he tells me that he checked my timing and it was way off! He said the rotor was pointing in the oposite direction is should be. Now just for the record I don't have a lot of faith in this shop (wich I will never go back to) but if he is right I'm chasing the wrong thing here. Short of a timming chain breaking is there any other way this thing could get that far out of time? Has any one ever heard of one of these 4.0's having a timming chain jump a gear? Or maybe the gear on the bootom of the distibutor breaking a tooth off?

 

[87manche]

it's possible that the gear in the bottom of the dizzy got stripped, this usually happend when the camshaft is worn and eats the gears.

search for "distributor index"
here on naxja, you'll find the procedure and be able to tell if your timing is way off.

 

[parkeruph]

This is becoming a REAL head scratcher. 2 yrs after the cylinder washout happened, was running good, parked for 2 wks and no start.
Had my grandson mechanic check it out with a digital multi-meter and he found a bad pick-up coil inside the dist. $79 at checker auto, $47 at Napa. This is on a 93, 4.0 cherokee Sport.
Don't know if your 90 has the same dist.
The replacement required removing the dist, knocking a roll pin out of gear on the shaft to remove the pickup coil. Black plastic with 2 wires going to it. Tricky to get the dist back in correctly. Possible to get it installed 1/2 off if you don't mark where the rotor is pointed before you remove the dist.
BUT, I don't think it would make a spark at the plugs if the pickup coil was bad.
Perhaps there's some-one out there that can explain how to check the pickup coil in place.
I know it's low voltage and a test light will not light up. maybe around 3.+ volts, not sure.
SOME_ONE out there that's smarter than I am, Please come to our rescue.

 

[Flash]

put your voltmeter to A/C and have some one spin the eng. don't now witch 2 wire you us but ya can fallow it out of the distributor.

Should produce .5 of a volt or better before the module will allow the coil to spark. if you have spark them this is not your problem.

here is how you find out if the dist is in time with the piston!!!!!!


remove #1 spark pug wire, remove spark plug and install it on the wire(make shore plug is clean and dry!)
Put a 3/8 extension over the hole of the missing spark plug(do not put it in the hole ) us the large end of the extension and cover the hole so that you can here the whooshing sound of the air as it is coming up on compression stroke.

Make sure that spark plug wire it attached the the spark plug, and that it is attached to a good ground.

Have your buddy crank the eng over while you hold the extension over the hole, and lisson to the swooshing sound and watch the spark!!!!!

If the sound of the air escaping the cylinder in in perfect time with the snap of the spark plug...........you are in time!!!!!! If not you have found the area of you problem.

 

[Ecomike]

I talked to the shop once more and now he tells me that he checked my timing and it was way off! He said the rotor was pointing in the oposite direction is should be. Now just for the record I don't have a lot of faith in this shop (wich I will never go back to) but if he is right I'm chasing the wrong thing here. Short of a timming chain breaking is there any other way this thing could get that far out of time? Has any one ever heard of one of these 4.0's having a timming chain jump a gear? Or maybe the gear on the bootom of the distibutor breaking a tooth off?

I was reading the other day that there are two top dead centers on cylinder #1 , one during compression (the one you want for proper timing of the spark) and the other during the exhaust stroke. If you installed the new distributor at TDC of the #1 cylinder during the exhaust stroke by mistake, it would put your timing off by exactly 180 degrees. The shop may have been right! That may be exactly your problem. Need to be sure and get the #1 cylinder at TDC on the compression stroke for setting the distributor timing.

Mike McGinness
South Houston, TX

 

[nate438]

That's just it, I have never had the disributor out of this jeep before. I think I agree with what 87manche said. I'm almost willing to bet that gear has a issue. Realisically after sitting a week and then not starting what else could cause the rotor to be way off other that a mechanical issue, like the dist gear chipped or broke a tooth. Is there really any way that an electical failuer of any sort would cause a change in the physical location of the rotor? I don't belive so but then again I cannot claim to be a mast wrench either, LOL.

My next step is going to put the engins at TDC and check for myself that the rotor is off, if it is then I'm going to pull the dist and see what that gear looks like.

 

[nate438]

I pulled the valve cover off to check the timing but how can I tell if the engine is top dead center on the compression or the exhaust stroke? When I turn the engine over on my way to top dead center and I hear the "whooshing" or sucking is that on the compression or the exhaust stroke? Either way I checked with the engine at top dead center of both strokes and the rotor never lines up with cylinder #1 on the distributer cap. I belive it's time to pull the distributer next and check the gear at the bottom unless you guys have any better ideas 1st?

 

[Flash]

With the valve cover off you will now witch TDC you on by the valves.

If both rocker arms are up, on #1 your on the compression stroke!

If you remove the distributor and the pin is shears off and the shaft or rotor spins free........you my have a sizing oil pump!

Did you ever do the wooosh snap test?

 

[rstarch345]

Seems to me a dead CPS causes the same symptoms. It would explain the 2 week sit and no start.

 

[nate438]

No I never did the whoosh snap test, I know I have spark but I just did not do that exact test but know I now for sure the timing is off based on the rotor being in the wrong position. I just replaced the CPS 2 days ago when this all started so I now it's good. I will pull the distributor on Tues and let you guys know what I find.

 

[churky89]

Not sure this is the problem...but if ECU is bad....it will not send a signal to the injectors....
I had a similar situation last summer
If your getting spark,what color is the spark...If it's yellow thats a sign there may be a problem with either the coil or the ignition module or both
CPS will do the same.....crank but not fire
I wound up with 4 things being fubared
ECM...not sure if it can be tested.....
COIL..can be tested
IGNITION MODULE...can be tested
CPS...broken wires
Most all the stuff I'v got on my XJ is original and I've had to replace each as it fails...

 

[langer1]

He said the rotor was pointing in the oposite direction is should be.

Lets stop there, thats not possible, a broken gear would not allow it to get that far off and still turn, is it turning? You don't need to pull it to see if it's turning.

If it looked like it was 180 deg out, could you have the wires on wrong?

Next after you check that, lets try a little shot of starting fluid down the air intake, unhook the air cleaner and give it a little shot.

Again don't pull the dizzy just yet, I really doubt it's out of time from just sitting, lets just make sure it is turning.

I'm still thinking, because you have not answered my question that you may not have enough spark at the plugs.

One more time, is it blue and will jump at least one inch at the plugs?

 

[nate438]

Ok I will try the starter fluid down the intake, and make sure the rotor is turning when I crank it over and I will check the spark color and size for sure and get back to you. Prob have to do that tomorrow Christmas eve today with the fam. I will let you know tomorrow am, thanks.

 

[jeepinandy]

This may sound stupid, but have you tried a timing light on it? It is possible it has jumped time. I know you said it had fairly low miles on it but anything can happen. And as langer1 mentioned make sure you have a GOOD SPARK. If it's not getting enough spark at the plug it isn't going to run no matter what you do.
Sorry couldn't be a whole lot of help..
Good luck

:cheers:

 

[Ecomike]

Lets stop there, thats not possible, a broken gear would not allow it to get that far off and still turn, is it turning? You don't need to pull it to see if it's turning.

If it looked like it was 180 deg out, could you have the wires on wrong?

Next after you check that, lets try a little shot of starting fluid down the air intake, unhook the air cleaner and give it a little shot.

Again don't pull the dizzy just yet, I really doubt it's out of time from just sitting, lets just make sure it is turning.

I'm still thinking, because you have not answered my question that you may not have enough spark at the plugs.

One more time, is it blue and will it jump at least one inch at the plugs?

First off langer1 has some good suggestions. But be carefull with the starter fluid. Use just one shot, no more, and do it only once. Too much can also keep it from starting, or worse damage the engine.

Pulling the injector connections (mark them first) and cranking the engine with them disconnected will dry out a flooded engine fairly fast! Just another option.

Also jeepinandy's suggestion of using a timing light makes a lot of sense, especially if the timing is changing due to bad teeth...a slipping something in the timing hardware, or if the distributor is not turning! The timing light would show this.

That said I have a comment and question (clarification request? not sure if I agree or not) on Langer1's statement "Lets stop there, thats not possible, a broken gear would not allow it to get that far off and still turn",

If a tooth was gone (not sure how likely that is) would it not slip time a bit each time (or occasionally at least) it indexed over that missing tooth area? In which case the timing would drift one tooths worth of degrees each time it completed a complete turn and slipped? Perhaps it would take the loss of several teeth first for it to be able to slip at all? Just thinking out loud, whatifing.

I do agree that you run the other tests they suggested before pulling the distibutor!

Mike McGinness
South Houston, TX

 

[nate438]

You hit it right on the head man! That is the same theory I had this whole time a physical break causing the issue. Here is my problem, question, issue if you will....

Is it possible for a electrical component, ecu, cps, tps, pdm, ignition module ect. to fail and cause the rotor to be physically off (out of time) of where it should be? If not then I don't even need to address any elctrical sensors or issues until I know what physically broke to casue this reaction. No one has been able to answer me this yet? That is why I belive it has to be a physical break of some sort not a electical issue. I can check for spark all day but the simple fact is I can see the rotor is way off time so I need to know what would cause this before I even worry about how mush spark I have, I can have perfect spark all day long and if it's never in time it isn't going to start. Like I said I belive there is a issue that I will find under the dist when I pull it out that will tell my why the rotor is off...

 

[langer1]

I see nothing you have posted anyway as to how you think the rotor is off.
Have you put the engine on TDC and the rotor is not on number one?
BTW the reason I think the dizzy don't have a bad gear it when something goes wrong and causes the gear to break it also stops it from turning at all.

The theory that it could break one tooth and keep turning is possible but just not very likely because what ever bound up tight enough to break the gear also would stop it from turning past the missing tooth.

Question, where do you think number one is on your dizzy.

No one has been able to answer me this yet?

Mostly because you have not answered most of the questions posters trying to help you have ask.

 

[parkeruph]

Top Dead Center=====
The way we determined TDC in the late 50's and early 60's was to have the valve cover off and

the flywheel cover off and have some-one underneath turning the flywheel with a flat

bladed screw driver, (I used a brake shoe adjusting tool), have them turn the eng over the
same direction the eng normally turns when running. The person on top watches the # 1 valve
rocker arms for the intake valve to open.

When it starts opening and sucking in fuel and the piston reaches the bottom and the cylinder

is full of fuel, the intake valve closes and then the piston returns to the top compressing

the gas and at this point the piston is TDC and is ready to fire which will actually be a few

degrees before TDC. Most engs are set to fire before TDC. Now you can stick a small phillips

screw driver in the sparkplug to confirm that the # 1 piston is on top. The rotor should be

pointed toward # 1 sparkplug wire within a few degrees. Some where near 3 to 5 degrees as best

as I remember. Hope this is not too confusing. If you have questions post them and I will post

back. In those days there was a timing mark on the harmonic balancer and gage on the timing

gear or chain cover that had markings to tell what degrees of advance or retard the dist rotor was at, when the timing light flashed or when # 1 fired.

 

[old_man]

Pulling the injector connections (mark them first) and cranking the engine with them disconnected will dry out a flooded engine fairly fast! Just another option.

Holding the TPS at WOT will also shut off the injectors. That is what I recommended on page one.