won't run - JeepForum.com
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post #1 of 12 Old 09-13-2020, 04:37 PM Thread Starter
flyingd
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won't run

I have a 93 stroked 4.0 in my new to me YJ............it is not running......i put a noid on number one injector and a light on the spark plug........the injector lights up before the spark plug........i changed the distributor a couple of teeth and no change........help me understand

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post #2 of 12 Old 09-14-2020, 06:38 AM
GTS225
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The noid will light before the plug because it's injecting fuel at the top of the intake stroke. After that, you have the compression stroke, then ignition, followed by the power stroke. Remember......intake, compression, power, exhaust, repeat.

Put the distributor back where it was and check for the presence of fuel.

Roger
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post #3 of 12 Old 09-14-2020, 08:10 AM Thread Starter
flyingd
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I am sorry. I wrote it wrong. The noid lights up after the spark. I have spark and then injection
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post #4 of 12 Old 09-14-2020, 01:52 PM
GTS225
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OK.....how much after? Half a revolution? One full revolution? If it's a full revolution, then you might be reading them out of order. Again, refer to the 4-cycle order.....intake, compression, power, exhaust.
Spark, then power stroke, then exhaust stroke, (injector firing at overlap), intake stroke, compression stroke, (spark firing at overlap), power stroke...repeat.

Is your check engine light flashing a code?

A good internet diagnosis is going to need some accurate details, sorry.

Roger
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post #5 of 12 Old 09-15-2020, 05:37 AM
Siva283
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Quote:
Originally Posted by flyingd View Post
I am sorry. I wrote it wrong. The noid lights up after the spark. I have spark and then injection
So you have spartk and power to the injector. You could be reading them out of order. Check for fuel. Do you hear the pump come on at key on? Have you checked pressure? You can have power at the injector without it spraying fuel. Also how strong is your spark.

Since you moved the dizzy set number one cylinder to top dead center on the compression stroke and set the dizzy to point at number one plug.

Then check your fuel system. I doubt the unjector pulse and spark are swapped. Usually its just there or not and hard to tell the order. Anything is possible but its highly unlikely they are firing out of order.
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post #6 of 12 Old 09-18-2020, 04:56 AM
fishadventure
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Sorta building on what siva said but did you confirm plug wires are in the right place on the distributor? (Although having said that if they were wrong there’s usually some excitement involved when you crank it if the wires are wrong)

I agree: put the distributor back where it was, and verify fuel pump run, presence of fuel at the rail, and pressure.

Also if fuel is over a month or two old you should probably get rid of it. Get some fresh non-ethanol fuel if you can.

A simple test is starting fluid or a small amount of gas in the throttle body. If it fires on either you at least know the mechanical is ok.
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[size=3]Shackles & D-rings are different things.
Cranking IS turning over
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post #7 of 12 Old 09-21-2020, 08:06 AM Thread Starter
flyingd
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I have checked everything mentioned and it was right. So I started back to the beginning and have just set the crank to TDC and set the cam. The crazy thing on the cam is that the timing mark is 180 off. don't know why and I know I have set the cam for compression. So next is a stick of dynamite, right? The PO replaced the crank sensor. I checked the TPS and it checked out. This is getting frustrating.
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post #8 of 12 Old 09-21-2020, 08:31 AM
fishadventure
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If it’s 180 off you are off 180* imho. Cuz that’s off.

The cam sprocket and the crank line up with dots that oppose each other. I don’t know the exact spec on the 4.0 but iirc that should leave the crank PULLEY timing mark 0* relating to the indicator degrees on the external casting. (A manual will tell you for certain but the casting and PULLEY mark will need to be either at ZERO or at X degrees as specified in the manual. I “feel” like dots aligned and once rotated to verify the chain pin-count 0* is correct but I’m doubting myself big time at the moment. Stuff doesn’t stick in my head like it used to.)

Anyway that process above will get you to TDC ignit cycle and rotor will be slightly past #1 distributor cap contact.

If that procedure verified out then the only conclusion is that you are 180* off and exhaust valve is just barely lifted. (TDC on the crank pulley happens twice for every cam revolution.)

[size=3]Shackles & D-rings are different things.
Cranking IS turning over
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post #9 of 12 Old 09-21-2020, 01:19 PM
GTS225
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Well, there is an explanation, but it's highly unlikely for your engine.
I'm also a Mopar slant six enthusiast, and there has been discoveries where the outer rind of the dampener had slipped in relation to the hub. The rubber ring in between had failed and separated, allowing the slippage to take place, but that's on an engine built in the 60's.
I'm inclined to think somebody (the PO?) may have installed a timing chain incorrectly, or your procedure for determining TDC on the compression stroke is faulty.

Roger
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post #10 of 12 Old 09-21-2020, 08:43 PM Thread Starter
flyingd
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Ok. I had a friend come over today, he and I have been working on cars since the 60s. We both understand how a 4 stroke works. that being said here is what we did.


With the chain off the pulley we set the crank at top dead center and the marks on the pulley gear lined up correctly


then we rotated the cam until it was in the compression stage, both valves up.



Put the cam gear on and the timing mark is 180 off. We checked it several times and it always came up the same. I do not understand How it could do that but we did time it right.


put the chain and gears on and rotated it and on compression stroke, at tdc the valves are both up.


checked the distributor and it is in correctly lined up on number 1.



checked and have correct pressure at the fuel rail.


cranked it and no go.


hooked up a noid to number 1 injector and while looking at the valves watched and the noid lit up at the bottom or so of the exhaust sequence.


pulled number 1 spark plug and did the same and it looked like it was firing at the correct time


have not checked the crank position sensor or the cam sensor


it did backfire twice during all of the cranking we did


so I quit for the night and until I can get some more ideas on what my next move is.


I understand that the computer tells the injectors when to fire, but what tells the computer that the time is correct



thanks for all the help


Larry
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post #11 of 12 Old 09-22-2020, 11:57 AM
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If your valves are up (off the seats) at TDC that’s wrong.

Also your description confused me a little, too. The dot alignment then rotate to the specific orientation and count the pins is the factory procedure iirc Once verified you go to TDC compression and THAT is when distributor is clocked. Someone will correct me I hope if I’m wrong but I believe that’s correct.

[size=3]Shackles & D-rings are different things.
Cranking IS turning over
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post #12 of 12 Old 09-25-2020, 12:36 PM
carlsflh
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heres a pic of the marks lined up this is a 95 4.0
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