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  1. #1

    Default 99 5.7 vortek cold start problem

    only on cold start cranking time is long with slight sputtering. spinning over real good. Eventually it fires up and immediately runs perfect the rest of the day. even if it sits several hours. Problem shows up only after sitting over night. Over night temps are from 50 to 60 degrees. No check engine light.

  2. #2

    Default

    1st thing I'd probably do would be to put a fuel pressure gauge on it and see if the pressure is coming up to 60 psi like it should before that first start.
    '98 K1500 Suburban LS 5.7 L 4L60E NV246 ARB
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  3. #3

    Default

    sounds like a fuel pressure regulator problem problem is on the 5.7 is a little difficult to check to see if it is leaking its under the plastic intake cover

    2003 Z71 Silverado LS
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  4. #4

    Default

    yeah i would check the pressure regulator im gettin a sputer on mine now after it sits cold for 6+ hours and its a common problem

  5. #5

    Default 5.7 cold start problem

    Sounds like I do need to check the fuel pressure regulator. I put a pressure tester and found the pressure at 60 psi as soon as the key is turned on and it holds that for a few minutes...after about 15 minutes it is down to about 50. As soon as I start cranking it the pressure drops from 60 to about 40 and it wont fire up. I need advice on how to test / gain access to the pressure regulator. Thanks for any help....

  6. #6
    Legend 2ToNe04's Avatar
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    Default

    check if your butterfly on the throttle body isnt sticking, and make sure you clean it.

    2004 4.8| Custom Paint| Tint| De-badged| Shaved Tailgate| Rollpan| Smoked Tails| Color Matched| Lowered 5/8| Suede Interior| Color Matched Interior| Indash & TVs| Mids-Lows & 2 12" CVRs| 500 & 1100 Interfires| Soundeadener| Outlaw CAI| Magnaflow|
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  7. #7

    Default fuel pressure ??

    No problem with the butterfly sticking... how do I gain access to the fuel pressure regulator to test it? Do i need to pull the intake? If the fuel pressure is dropping down to 40 during cranking is that a sure sign of a regulator or pump problem?

  8. #8

    Default

    Pressure dropping to 40 is probably why it won't start (I've heard it said those poppet valves need at least 50 psi just to open).

    You don't necessarily "need" to physically get at the regulator to test it further. The regulator is a basic back pressure regulator. To test it further you simply need to determine if the regulator is "open" and letting fuel return to the tank when the pressure is low. Some people don't like the idea, but the usual suggestion is to repeat the test you did. Then, when the pressure is too low (40 psi), use a suitable tool and clamp off a rubber section of the return line. If the pressure spikes up, then the regulator was open when it shouldn't have been and you strongly suspect the regulator is bad. If the pressure remains too low, then you suspect something is wrong with the fuel pump or there's a restriction/clog in the fuel filter/lines between the pump and the regulator.

  9. #9

    Default

    Mr Shorty has it right on the nose.
    When you hear hoofbeats, look for horses not zebras.

  10. #10
    Master Mechanic CarpenterGuy's Avatar
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    Default

    could the gas just be condensing in the lines?
    2006 Silverado Z71 - 97,000 - totaled, RIP
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