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Engine shuts off right away and backfires

Tiny
ASHLEE MARIE
  • MEMBER
  • 1999 PONTIAC BONNEVILLE
  • 3.8L
  • 6 CYL
  • AUTOMATIC
  • 196,000 MILES
Okay so I'm hopeless about my car. I have the car listed above SE model. Not supercharged. Originally the engine would turn on and it would start but then shut off after a couple seconds. Then I changed the EGR valve and the Mass Airflow sensor, and spark plug wires and it would run for longer and stay idling. But when I put it into gear it would shut off and backfire. Then I changed the spark plugs because the scanner was throwing a random cylinder misfire, which was I assumed to be spark plugs because I just replaced the coils and the wires and everything. Now I try to start it and it's back to square one. Shuts off right away and backfires. I've put over $350.00 into this thing to fix it and I still can't figure it out.
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Thursday, June 13th, 2019 AT 12:58 AM

22 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning,

Did you or anyone check the fuel pressure? It sounds like you need a fuel pump.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

https://www.2carpros.com/articles/engine-stalls

https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump

Can you tell me the code number you had?

Roy
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Thursday, June 13th, 2019 AT 5:25 AM
Tiny
ASHLEE MARIE
  • MEMBER
  • 13 POSTS
We checked fuel pressure. It's coming out in a clean stream. I can't get it to move to get someone to check it for me. It is throwing a po300 multiple cylinder misfire.
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Thursday, June 13th, 2019 AT 12:07 PM
Tiny
ASEMASTER6371
  • MECHANIC
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I need the exact pressure. If it is too low, it will not run.

Roy
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Thursday, June 13th, 2019 AT 1:13 PM
Tiny
ASHLEE MARIE
  • MEMBER
  • 13 POSTS
I don't have the tools for the exact pressure right now so I'd have to get it first.
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-1
Thursday, June 13th, 2019 AT 2:43 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
That's okay, I will be here. I need that to continue to help.

Roy
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Thursday, June 13th, 2019 AT 4:01 PM
Tiny
ASHLEE MARIE
  • MEMBER
  • 13 POSTS
What are the chances it could be head gasket or timing chain?
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Thursday, June 13th, 2019 AT 7:37 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
It is possible but need to verify basics before going to much larger issues.

Roy
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Thursday, June 13th, 2019 AT 11:18 PM
Tiny
ASHLEE MARIE
  • MEMBER
  • 13 POSTS
I don't remember what it was reading but I was told it is fuel pressure regulator. How do I properly replace it? I have all the tools and such for it.
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Tuesday, June 18th, 2019 AT 6:41 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Procedure below:

Roy

1. Relieve the fuel pressure. Refer to Fuel Pressure Relief Procedure. See: Fuel Pressure Release > Procedures

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2. Clean any dirt from the fuel pressure regulator retaining ring.
3. Remove the vacuum hose from fuel pressure regulator.

ImageOpen In New TabZoom/Print

4. Remove the snap ring (7) from the fuel pressure regulator.
5. Using a shop towel to catch any spilled fuel, lift and twist the fuel pressure regulator in order to remove the fuel pressure regulator (6) from the fuel pressure regulator housing (1).
6. Remove the regulator O-ring small (2).
7. Remove the regulator filter screen (3).
8. Remove the regulator O-ring large (4).
9. Remove the regulator O-ring back up (5).
10. Cover the fuel pressure regulator housing (1) to prevent contamination from entering the fuel system.
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Wednesday, June 19th, 2019 AT 2:41 AM
Tiny
ASHLEE MARIE
  • MEMBER
  • 13 POSTS
I was told I have to remove parts out of my car. The intake manifold gasket and such. That's what I'm the most confused about.
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Wednesday, June 19th, 2019 AT 4:07 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
That is inaccurate information.

The regulator is on the fuel rail in the back by the last cylinder at the firewall.

Roy
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Wednesday, June 19th, 2019 AT 4:32 AM
Tiny
ASHLEE MARIE
  • MEMBER
  • 13 POSTS
This. Correct?
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Wednesday, June 19th, 2019 AT 7:25 AM
Tiny
ASEMASTER6371
  • MECHANIC
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Yep. That is it.

Roy
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Wednesday, June 19th, 2019 AT 7:32 AM
Tiny
ASHLEE MARIE
  • MEMBER
  • 13 POSTS
Well then I bought an intake manifold for no reason. Yay. Alright I'm going to try this really quick.
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Wednesday, June 19th, 2019 AT 7:37 AM
Tiny
ASEMASTER6371
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Okay.

Roy
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Wednesday, June 19th, 2019 AT 7:42 AM
Tiny
ASHLEE MARIE
  • MEMBER
  • 13 POSTS
It's not letting me go to the link to see how to release fuel pressure.
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Wednesday, June 19th, 2019 AT 7:42 AM
Tiny
ASEMASTER6371
  • MECHANIC
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Just loosen the line slowly until the pressure bleeds off.

Roy
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Wednesday, June 19th, 2019 AT 9:26 AM
Tiny
ASHLEE MARIE
  • MEMBER
  • 13 POSTS
Got pressure tested. It's fine.
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Wednesday, June 19th, 2019 AT 12:13 PM
Tiny
ASHLEE MARIE
  • MEMBER
  • 13 POSTS
It runs and drives now. It just shuts off usually only when pulling into parking spots. It does not shut off when driving. Still throwing po300.
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Wednesday, June 19th, 2019 AT 12:19 PM
Tiny
ASEMASTER6371
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What t.C is the fuel pressure?

Roy
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Wednesday, June 19th, 2019 AT 12:29 PM

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