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Long Start After Sitting

Discussion in 'General Chevy & GM Tech Questions' started by Tom Evans, Oct 15, 2011.

  1. Tom Evans

    Tom Evans Rockstar

    I have a 2002 Suburban with the 5.3 L Flex Fuel engine with 128,000 miles. It is not driven every day. Sometimes it can go a week without being driven. In the past it always fired up immediately. About two months ago, the fuel filter clogged on me and it wouldn't start at all. I replaced the filter and all appeared well. However, now if I leave it a week without driving, it doesn't want to start. I have to cycle the ignition switch about three times before it will start. After the first start, I am good to go the rest of the day. I have checked the fuel pressure and it is on the low extreme of acceptable pressure.

    Any thoughts?
  2. timhall1787

    timhall1787 New Member

    are you losing fuel psi back to the tank? regulator?
  3. Tom Evans

    Tom Evans Rockstar

    How can I tell where I am losing fuel PSI? I have a fuel pessure gauge that I could leave connected to the test port on the fuel injection rail. I guess if I lose presure there, it would be due to the regulator. I did have the intake manifold and hence the fuel rails removed recently as I replaced both knock sensors. I didn't do anything special to the fuel system after I re-installed the intake manifold. Could that be the source of my problem?
  4. Tom Evans

    Tom Evans Rockstar

    I semi-permanently attached a fuel pressure gauge to the fuel rail. The Chevy shop manual states that the fuel rail should not drop more than 5 PSI in one minute's time after shutting the enigne off. I lose some pressure, but am within the 5 PSI spec. If I let it set overnight, the pressure is down to 0 PSI. However, it will start right up the next day.

    The problem occurs when I let it set for a week. It takes forever to crank.

    I plan to leave the fuel pressure gauge attached and leave it for a week to see what happens to the fuel pressure registers before I crank.

    Any ideas? Could the fuel rail pressure regulator be slowly letting the fuel in the fuel rails drain back to the tank?
  5. Tom Evans

    Tom Evans Rockstar

    Long Start After Sitting a Week

    I have a 2002 Chevy Suburban with a 5.3L Flex Fuel engine with 128,000 miles. I don't drive it everyday. When I do drive it everyday, it starts right up everytime. However, lately when I have gone a week without driving it, it takes a lot of cranking before it starts.

    Here is what I have done:

    1. Replaced fuel filter.
    2. Hooked fuel pressure gauge to the fuel rail. The pressure is correct according to the Chevy shop manual for both before cranking and while running.
    3. The 1 minute leak down test (<5PSI) is correct.
    4. When I let it sit overnight, the fuel pressure goes down to 0 PSI, but the engine always cranks quickly.

    I'm going to leave the gauge connected and let the Suburban sit for a week and see how it cranks while watching the gauge.

    Does anyone have any ideas? Could it be the fuel rail pressure regulator letting the fuel drain out of the fuel rail and back into the tank? Is there a check valve in the fuel pump that could be malfunctioning which allows the fuel to drain back to the tank?

    Thanks.
  6. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    It could be either the Fuel Pressure regulator, or the check valve on the pump. but i would lean twards the FPR. one way to see if you have a faulty unit is to take off the vaccum line after it has been running and see if fuel is present. if so then you for sure have a bad FPR. or else try cycling the key several times letting the pump run each time. And see if that allows it to start faster. this is also a sign of a bad FPR.
  7. Crawdaddy

    Crawdaddy Thread Killer Extraordinaire Staff Member 5+ Years 1000 Posts Platinum Contributor

    Duplicate threads merged. Do not cross-post in different sub-forums.

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