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Cranks but no start

Tiny
68GTOCONV1
  • MEMBER
  • 1997 JEEP WRANGLER
  • 2.5L
  • 4 CYL
  • 4WD
  • MANUAL
  • 104,000 MILES
I have a no start problem. All sensors are new, ASD is functioning fine. No spark and no injector pulse. All fuses are good and I have full power at the pdb.
Wednesday, November 20th, 2019 AT 3:30 PM

6 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Have you check for a crankshaft sensor signal? The PCM uses the crank to determine spark and fuel timing.

I included a test for no starts but I would just jump to the PCM and see if the crank has a signal. It would be great to see a lab scope pattern of it but since you don't have spark or fuel, I imagine the crank sensor is the issue.
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Thursday, September 24th, 2020 AT 6:18 PM
Tiny
68GTOCONV1
  • MEMBER
  • 4 POSTS
Yes, I replaced the engine and all sensors are new I even warrantied them out and replaced them again. All gauges work, tachometer does not bounce when cranking. ASD clicks on. All pin checks are good. I am about to ripe apart harness to see if I have a broken wire, but this thing has me very flustered.
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Thursday, September 24th, 2020 AT 6:18 PM
Tiny
68GTOCONV1
  • MEMBER
  • 4 POSTS
Also, I can't remember if I should have constant power at pdb under hood with key off because currently I do.
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Thursday, September 24th, 2020 AT 6:18 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Are you referring to the Power Distribution Center (PDC)? And when you say constant power, you mean on the feed wire from the battery? If so, then yes. This is normal.

Did this issue start after the motor replacement? Meaning did you do the engine and then this happened or has it been running since the engine has been put in? In other words, has it ever run since you replace the engine?
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Thursday, September 24th, 2020 AT 6:18 PM
Tiny
68GTOCONV1
  • MEMBER
  • 4 POSTS
Yes, the vehicle ran great for about 4 months and all the fuses in the PDC have power all the time key on or key off doesn't matter. It ran great then had I little stumble and then shut off no spark and no injector pulse.
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Thursday, September 24th, 2020 AT 6:18 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. I suspect the PCM is the issue if you have no spark or fuel and it is getting a crank signal.

Run through this test or just jump to step 7 and run that jumper and see if you get spark. If you do then you need a PCM and that may fix both issues.
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Thursday, September 24th, 2020 AT 6:18 PM

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