No start issue

2003 HOLDEN COMMODORE
80,000 MILES • 3.8L • RWD • AUTOMATIC
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OLEUM CHIN
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  • 3 POSTS
My vehicle tries to start, but only runs for a few seconds and when it does it is like the injector timing is off. It runs very rough if I spay gas down the intake it runs sweet for a for a few seconds then dies. I have installed a new fuel pump and filter, pressure at rail is fine. I had a new crank and cam censors installed, also tried plugs coil packs and o2 censor. I had it scanned no faults came up. I Do not know what to try next any help would be great. Thanks
Jun 10, 2016 at 2:00 PM
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MHPAUTOS
  • ✓Experienced Mechanic
  • 31,937 POSTS
You will have to inspect for injection pulse, the injection timing cannot be altered it is controlled by the ECU, a crank position sensor can cause this problem, you say that you have replaced this, was it the correct unit? go check the injection pulse first and let me know what you find.
Jun 10, 2016 at 8:21 PM
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OLEUM CHIN
  • MEMBER
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Hi, thanks so much for your help. I have had a mate come have a look he is an auto sparky, the injectors are pulsing and the crank position censor is the correct one, he scanned the car again no faults came up. We spent hours trying to sort it, but still no joy. it hast him beat. We checked the pressure at fuel rail and it is fine. What else could it be? Got me beat, haha! Once again thanks for your help.
Jun 11, 2016 at 6:26 AM
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MHPAUTOS
  • ✓Experienced Mechanic
  • 31,937 POSTS
Can you check if you loose rail pressure when it shuts off?if it will run with fuel down the intake it sounds very much like it is fuel related, i would run it with the pressure gauge on the rail and see what it does and also check for flow, yor flow may be well down as well, try this.
Jun 11, 2016 at 10:33 AM
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