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Spark plug gaping

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Old May 26, 2011 | 02:50 PM
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Default Spark plug gaping

Anyone know proper gaping for a,95 xj sport? Thanks guys
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Old May 26, 2011 | 03:15 PM
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.035 is the gap for all Jeep 4.0 XJ engines.
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Old May 26, 2011 | 03:46 PM
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Thanks. I need help then. I just changed my cap, rotor, and plugs, and she still won't start... Help
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Old May 26, 2011 | 06:45 PM
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Spark + fuel (plus compression and air) = START.

You need to determine what part of the above equation you are missing. Assuming the engine has been running well recently, most people are missing spark or fuel.

Always verify spark first. Take out a plug, keep it attached to the plug wire, place the plug electrode near a good engine ground, have a buddy crank the engine while you watch. 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.

If you have a STRONG spark (and only if), move onto fuel. Spray a small amount of starting fluid into the intake, or a small splash of gas. If the engine starts and runs for a short time with this technique, you have confirmed a "fuel delivery" problem.

The above tests go a long ways in isolating the root cause of a no-start.

Report back what you find.
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Old May 26, 2011 | 08:49 PM
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check your crank sensor also. that controls both fuel pump and spark.
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Old May 26, 2011 | 09:39 PM
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Originally Posted by tjwalker
Spark + fuel (plus compression and air) = START.

You need to determine what part of the above equation you are missing. Assuming the engine has been running well recently, most people are missing spark or fuel.

Always verify spark first. Take out a plug, keep it attached to the plug wire, place the plug electrode near a good engine ground, have a buddy crank the engine while you watch. 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.

If you have a STRONG spark (and only if), move onto fuel. Spray a small amount of starting fluid into the intake, or a small splash of gas. If the engine starts and runs for a short time with this technique, you have confirmed a "fuel delivery" problem.

The above tests go a long ways in isolating the root cause of a no-start.

Report back what you find.
So wrapped up for the night at 830 had to go pick up my girl from work. So tomorrow weather permitting im going to change out the coil pack as there is no spark whatsoever. And if that dosnt do it i will move to the crank sensor. and take it from there. Apparently these coil are notorious for going out, so lets just hope its that. on the bright side i will have a whole other tuneup kit when it gets here from summit.... Thanks for all the help guys.
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Old May 27, 2011 | 06:05 AM
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No coil pack on a 95. But you do have an ignition coil.

But now that you have verified there is no spark, the #1 cause is absolutely the crankshaft position sensor.

Everyone with a 4.0 needs to commit the above to memory!

Last edited by tjwalker; May 28, 2011 at 05:42 AM.
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Old May 27, 2011 | 09:20 AM
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Yup def ment ignition coil not coil pack my bad. I was dead tired last night. Thanks for the help tj. So you sayin its most prob the csps?
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Old May 27, 2011 | 09:35 AM
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Originally Posted by XJnLvilleGA
So tomorrow weather permitting im going to change out the coil pack as there is no spark whatsoever.
Didnt you say it ran fine before you changed the plugs? Unless you broke the coil it shouldnt go bad on its on sitting there.
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Old May 27, 2011 | 10:59 AM
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No. it was running the nite before. Left it over night. When I came to get it she wouldnt crank. Since then I have checked my fuel pump, recently changed my fuel filter and regulator. So I checked for spark first. When I realized there was none I changed the cap rotor and plugs. Still, nothing. Im actually trying to get over to it now to change that coil.
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Old May 27, 2011 | 08:57 PM
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Cps! She runs..... Bahahahahahaha
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