1998 Jeep Cherokee Crank no start

Tiny
SKITTLEMA94
  • MEMBER
  • 1998 JEEP CHEROKEE
  • 4.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 100,780 MILES
Bought jeep with blown head gasket, replaced head gasket. Got everything hooked up like should be, running header right Now. Go to start it, it just cranks, I put a battery in it from a daily driver, so I know I got power, got fuel, got spark, and air, but no start, cranks no problem but won't start.
Saturday, October 24th, 2015 AT 3:01 PM

8 Replies

Tiny
WRENCHTECH
  • MECHANIC
  • 20,757 POSTS
Did you send the head out to a machine shop for testing before putting it back on?
Those 4.0s are notorious for cracking heads when overheated, not just head gaskets.
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Tuesday, December 17th, 2019 AT 7:06 PM
Tiny
SKITTLEMA94
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No I don't have time for that, I just gotta get it running so I can get it out of my grandparents garage.
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Tuesday, December 17th, 2019 AT 7:06 PM
Tiny
WRENCHTECH
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All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.

Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.

2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.

4) If all of these things check good, then you would need to do a complete compression test.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
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Tuesday, December 17th, 2019 AT 7:06 PM
Tiny
SKITTLEMA94
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It has spark, I check that, I know it's. Getting gas, can smell it, we checked the bleed off valve on the rail. Fuel came out with decent pressure. I can see about a compression test if the tester is still at the house. Grandparents are in process of moving
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Tuesday, December 17th, 2019 AT 7:06 PM
Tiny
WRENCHTECH
  • MECHANIC
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"Decent pressure" doesn't cut it. You need to know the exact pressure.

You could try shooting a little starting fluid into the intake and see if it starts then.
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Tuesday, December 17th, 2019 AT 7:06 PM
Tiny
SKITTLEMA94
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Update, tried starting fluid didn't work, did compression test on #2 & #5 wasn't even hitting 30psi on the tester, keep wants to fire but can't
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Tuesday, December 17th, 2019 AT 7:06 PM
Tiny
WRENCHTECH
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Can't run with no compression. Time to look for a motor.
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Tuesday, December 17th, 2019 AT 7:06 PM
Tiny
SKITTLEMA94
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Update. Pressuzied 3 different cyl to 40psi, and heard some air, so should I get head redone?
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Tuesday, December 17th, 2019 AT 7:06 PM

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