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  1. #1

    Default 2000 Silverado Crank 3 times to start

    Newbie here, thanks for any advice you can give.

    My 2000 Silverado (105k) doesn't want to start until the third time cranking on cold starts, or even after sitting for 15 minutes or more. The 3 times rule goes for cranking the engine, or for just turning the ignition on for a few seconds, off for a few seconds, on for a few seconds... 3 times.

    I replaced the fuel filter a week ago. The old filter was definitely in need of replacement and was fairly clogged up.

    I swapped the horn and fuel pump relays (identical) and no change in symptom.

    I pulled the vacuum line from the fuel pressure regulator and it was bone dry, not even a trace of fuel.

    (MAF sensor was replaced too, fixing some bogging above 3k rpm)

    So, I'm unfortunately leaning towards a fuel pump.

    Book says 55-62psi with key ON engine OFF. I heard that Autozone could check fuel pressure. Am I just watching to see what the pressure looks like after the 1st, 2nd, and 3rd times I cycle the key? What should I be looking for?

    What else should I be looking at?

  2. #2
    Jr. Apprentice
    Join Date
    May 2010
    Location
    Colville, WA
    Posts
    20

    Default

    With the fuel pressure gauge attached, turn the key on (engine off). Don't cyle the ignition on/off two or three times. As you said, pressure should be 55-62 psi. Watch the gauge. The pressure should drop no more than 5 psi in 10 minutes.

    A fuel system that drops more than 5 psi in 10 minutes has a leak in one or more of the following areas:

    The fuel pump check valve
    The fuel pump flex pipe
    The valve or valve seat within the fuel pressure regulator
    The fuel injectors

    Relieve the pressure to 10 psi and watch the gauge for 10 minutes. The pressure should not drop more than 2 psi in 10 minutes. If it does, this would also indicate a leaking check valve in the fuel pump.

    The only way to check the fuel pump flex pipe is in the tank so you'll have to take the fuel pump assembly out of the tank to inspect that.

    You've already checked the fuel pressure relief valve. There shouldn't be any fuel in the vacuum line which indicates the diaphram isn't leaking but doesn't indicate if it's stuck open thus relieving pressure unnecessarily. I'd disconnect the valve and plug the line on the pressure side of the valve. Try to start the truck again and see if it starts on the first try.

    To check the fuel injectors, you'll need to do an injector balance check. To do this you will need a Tech II or a Snapon tool with bidirectional controls in order to activate each injector to see what they are doing. But, most likely, this isn't your problem. You would probably have a rough engine idle or possibly throwing rich codes if this were the case.

    I hope this helps some. Others on the forum may have other ideas. Good luck and let us know what you find.
    2000 Chevy Silverado 1500 ECSB Z71 5.3L LM7

  3. #3

    Default

    Thanks, that was a great post! I know very little about working on trucks, but I'm willing to read, learn, and try.

    I should have mentioned, it isn't throwing any codes. Idle is smooth. It is the 5.3L.

    Quote Originally Posted by rmck490
    Relieve the pressure to 10 psi and watch the gauge for 10 minutes. The pressure should not drop more than 2 psi in 10 minutes. If it does, this would also indicate a leaking check valve in the fuel pump.
    How do I relieve the pressure to 10psi?

  4. #4
    Jr. Apprentice
    Join Date
    May 2010
    Location
    Colville, WA
    Posts
    20

    Default

    The fuel pressure testing gauge you can use from Autozone should have a button on it to relieve the pressure. There should also be a long clear tube that allows gas to drain into a container on the gauge as well.

    There will be a fuel rail port on the right bank to attached the gauge to. Connect the fuel gauge to this port. Route the drain tube to a container off to the side of the truck. This should be done outside away from ignition sources. Turn the ignition on for a few seconds and then turn off. Relieve the pressure with the button into the container. Do this two or three more times to build up the line pressure to the maximum attainable to insure you get a good fuel pressure reading to work from.

    When you want to relieve pressure only 10 psi, gingerly press the relief button part way. It will bleed down slowly. Release the button when it reaches 10 psi.
    2000 Chevy Silverado 1500 ECSB Z71 5.3L LM7

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