Crank no start, how many PSI for the fuel pressure?

2002 ISUZU NPR
384,000 MILES • 5.7L • V8 • 2WD • AUTOMATIC
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BOBF22
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The engine cranks but will not start. I have spark, and fuel. The fuel pressure is at 42 PSI with the ignition in the on position. I believe that this fuel pressure is too low to start the engine. Could you please tell me what the fuel pressure should be for this truck.
Aug 10, 2021 at 3:37 AM
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SQM
  • ✓Experienced Mechanic
  • 6,383 POSTS
Hello,

This Isuzu uses a Chevrolet V8. The fuel pressure for those are 60-66 PSI with the key On and engine Off. So 42 PSI is a bit low.
Might be a issue with the fuel pressure regulator.

https://youtu.be/aITQclp7zIE

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

Unfortunately I do not have diagrams for the medium duty trucks for I am unable to provide you with one. But the regulator is similar to the diagram pictured below.

Please let me know what you find.

Thank you.
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Professional Diagram for 2CarPros Members
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Aug 11, 2021 at 5:52 AM
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BOBF22
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Thank you for your quick response. The problem was the fuel pump. I replaced the fuel pump, and now the fuel pressure is at 65 PSI with the key On and engine Off. The truck starts up now, and is running like it's supposed to.

Thanks again, for your help.
Aug 11, 2021 at 8:42 PM
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SQM
  • ✓Experienced Mechanic
  • 6,383 POSTS
That is great news.
Glad that you got it fixed.
Feel free to reach out to us should you have any questions in the future.

https://www.sitejabber.com/reviews/2carpros.com

Aug 11, 2021 at 11:06 PM
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