Fuel lines draining when sitting?

Discussion in 'GM Powertrain' started by riata_ag, Feb 27, 2010.

  1. riata_ag

    riata_ag New Member

    2001 Z71 Chevy Surburban with 5.3

    When the burb sits for more than about 30 minutes you have to cycle the key 3-5 times and then it will start.

    When it sits over night you have to cycle the key 5-9 times to get it to start.

    The starter engages and the engine turns over, has air and fire just no fuel.

    I read somewhere that the in-tank pump has a built-in check valve so today I put a new pump in - still have the same problem.

    Has anyone else ever experienced this or have an idea what the problem might be?

    Is it possible something is wrong with the pressure regulator and allowing the supply line to siphon through the pressure regulator and back into the tank through the return line?

  2. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    I wouldn't think so. the regulator is a pretty basic back pressure regulator, and shouldn't have issues closing off when the pump isn't running. I would think, if it was siphoning back to the tank through the regulator, the regulator also wouldn't close off enough to build up sufficient pressure to run the engine. Have you put a fuel pressure gauge on it to verify that the pressure is bleeding off after shut down? You could clamp the return line (or something like that) to see if the pressure continued to bleed down (which would eliminate the suggested possbility).
    Last edited: Feb 27, 2010
  3. crossleysierra

    crossleysierra New Member

    this probaly isnt what u want here, but most likely to be your prob is in the tank, i have ran into this several times with costomers , is your fuel pump is connected to the sending unit fuel line by a rubber hose they tend to break down and the rubber hose swells and will leak, its a cheap and easy fix to do yourself the only problem is its time consuming good luck let me know what you find :great:
  4. Z71_guy

    Z71_guy Epic Member 5+ Years 1000 Posts

    sounds like a common fuel pressure regulator extended cranks after sitting, easy to check just pull the vacuum line off the regulator and see if there is any gas what so ever if there is replace it
  5. silveradotrailblazer

    silveradotrailblazer Epic Member 5+ Years ROTM Winner 5000 Posts

    Leaking injecters?
  6. riata_ag

    riata_ag New Member


    Yesterday I replaced the fuel pressure regualtor. I too had read that gas in the vacum line signaled faulty regualator.

    When I removed the vacum line it was DRY. I replaced the regualtor anyway.

    I tested the vehicle twice last night after sitting for about 2 hours each and the engine fired up with the first turn of the key.

    Had to cycle the key twice this morning, so, full tank of gas, new fuel pump and new fuel pressure regulator and the problem is better, but not solved.

    Hope I don't have to go to the dealership on this one.

    I bought a fuel pressure guage at O'reilly's yesterday but for whatever the reason I didn't have it luck getting it to screw on the schrader valve port far enough to work, planning to return this morning.

    Any suggestions on a quality fuel pressure guage and adapter to order online, looks like I need to determine for a fact if I am losing fuel pressure, or there is some other issue.

    Last edited: Mar 1, 2010
  7. riata_ag

    riata_ag New Member

    Just posting back with an update on this problem:

    Checked the fuel pressure and it is NOT bleeding off.

    I pulled a plug to check the spark and there was no spark upon first try, but, after cycling the key 4 or 5 times the plug I had out sparked and the engine started.

    I had no idea of the problem, so I took it to a good dealer which I have used before and they worked on it for 2 weeks and could not find the problem.

    They did replace the crankshaft sensor and thought that fixed it; but it didn't.

    We could not do without the vehicle any longer and so now my wife is back to driving it, but she does have to cycle the key to get it to start whenever it sits for longer than about 1 hour.

    Anybody seen this before or have any ideas?


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