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Thread: Perhaps Too Much Fuel Pressure?

  1. #1
    Join Date
    Jul 2014
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    Boise, ID
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    Post Perhaps Too Much Fuel Pressure?

    I still have, for the most part, a stock 5.3 from a 2008 Tahoe in my 88 K5 Blazer, so we're talking 330 to 350hp at most. I do have some JBA headers that give it a little more, but not much.

    Anyway, I have a pump I bought from Summit that dropped into the Blazer's stock sending unit fine, and I've been running it for about 7 months now. It puts out 90 psi, and I've always noticed that the truck is running rich. I think this is bad (Disclaimer: I'm not a professional mechanic!)

    Is 90 psi for my setup too much? Can/will this cause problems, and if so, what?

  2. #2
    Join Date
    Apr 2014
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    What is the fuel pressure at the rail? The regulator should kick it down where it belongs unless the pump is just flat over coming the regulator.

  3. #3
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    Pressure at the rail:

    (key turned but engine not started is 55psi)
    (Engine started is 90psi)

  4. #4
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    San Marcos Texas
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    60 is about right. 90 is too high.

  5. #5
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    Jul 2014
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    Boise, ID
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    Thanks! Looks like I'll be dropping the tank again here shortly.

  6. #6
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    St. Anthony, Indiana
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    Are you using a fuel pressure regulator?

  7. #7
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    Jan 2016
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    Too much pressure unless you're running a lot more HP than stock. I don't know what harm it would do other than run rich and throw o2 errors.

  8. #8
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    Quote Originally Posted by foggy View Post
    Are you using a fuel pressure regulator?
    Yes. Got a corvette/wix regulator hooked in shortly after leaving the tank. The rail on my motor doesn't have one built in - some didn't in 2008.

  9. #9
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    Quote Originally Posted by GotaluvHP View Post
    Too much pressure unless you're running a lot more HP than stock. I don't know what harm it would do other than run rich and throw o2 errors.
    That explains the engine running rich - no codes tripping, though.

  10. #10
    Join Date
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    Quote Originally Posted by 88blazerboy View Post
    Yes. Got a corvette/wix regulator hooked in shortly after leaving the tank. The rail on my motor doesn't have one built in - some didn't in 2008.
    I would think that you have a bad regulator than. It should regulate it to about 60 psi.
    How is your fuel system set up?

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