Crank no start it backfired once?

Tiny
TLSTEELE 296
  • MEMBER
  • 2003 OLDSMOBILE ALERO
  • 3.4L
  • V6
  • 2WD
  • AUTOMATIC
  • 20,000 MILES
I just finished replacing the head gaskets and got everything back together got oil in it I don't have coolant in the motor yet. I just want to give you the background to bring you up to date LOL I went I charge the battery went cranking over Crank crank Crank but no start it backfired once. I noticed two vacuum lines sticking out one's black real small traced it back to the fuel pressure regulator I believe. The other is real small and white and it came out of a a bunch that I thought were wires and anyway it's stuck in there and It was just poking out I took pictures and marked them if you could tell me where this white vacuum hose supposed to end up where it started and if I'm correct about the black one it goes from a pressure regulator to the it looks like a fuel filter on the fuel rail on the other end. Appreciate the help I'll send pictures also
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Monday, April 6th, 2026 AT 9:47 AM

7 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 55,411 POSTS
So the arrow on the intake manifold is a large vacuum leak so plug that or find the line that goes to it, the blue line goes to the fuel pressure regulator which is just in front of it, and the white line goes to the HVAC system and needs direct vacuum. Please send me a short video of the engine trying to start after that so I can see what is going on. Ken This video may help as well.

https://www.youtube.com/watch?v=lXLJbuAZ4CE&t

Please go over this guide and get back to us.

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Tuesday, April 7th, 2026 AT 10:22 AM
Tiny
TLSTEELE 296
  • MEMBER
  • 9 POSTS
Got the vacuum line figured out it fired several times but dies right away my exhaust is not connected I had to cut it to access rear head. I had to feather the pedal quite a bit to keep it going
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Wednesday, April 8th, 2026 AT 12:37 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 55,411 POSTS
Thanks for the video, it looks like the firing order is wrong, I would double check that first. These images should help. Check out the images (below). Please let us know what happens.
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Thursday, April 9th, 2026 AT 6:19 AM
Tiny
TLSTEELE 296
  • MEMBER
  • 9 POSTS
I ran the wires according to the diagram it starts but won't idle, still sounds like back firing
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Friday, April 10th, 2026 AT 3:33 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 55,411 POSTS
Thanks for the video, it still sounds like the firing order it off, I would check it again. Also, UI have seen these kinds of ignition coils go bad and crossfire which can be the problem as well. Also, check the engine wiring harness grounds to the engine, if the system has a bad ground it will cause this issue as well, if everything looks okay run the codes, I seen the check engine light on, so codes are stored and get back to me, we are close to getting the engine running good.
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Saturday, April 11th, 2026 AT 7:48 AM
Tiny
TLSTEELE 296
  • MEMBER
  • 9 POSTS
The only code that came up was P050 the wires are correct how would I check the ignition coils?
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Monday, April 13th, 2026 AT 9:31 AM
Tiny
TLSTEELE 296
  • MEMBER
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Nevermind the code I'm getting is P0300
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Monday, April 13th, 2026 AT 2:39 PM

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