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New guy with a 99 sub 1500 has a ? hesitation problem.

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by Pat10, Mar 29, 2012.

  1. Pat10

    Pat10 New Member

    Hey everyone I'm new here, I bought a 99 suburban a yr ago with 100k miles.
    I've had the intake gasket replaced new brakes and tires since, Now when I start up put in drive if I try and give it any good pressure on the pedal it hesitates. From my driveway it takes about halfway down the block for the power to kick in.
    It seems to only do this on start up and initial acceleration, not at any other speeds not taking of from stops.
    I tested it by driving around for awhile stopping turn off turn back on and go and did it's few second hesitation.
    Did this several times, same each time.

    Any help,suggestions would be great!
  2. Naptime

    Naptime New Member

    Fuel pressure? You're at that milage range for the regulator and fuel pump switch out.
  3. Pat10

    Pat10 New Member

    OK, I'm at 112k right now and I've heard about the fuel pumps on these things. Mine has had a noticeable buzzing sound when standing outside the cab,
    but it's done this since I got it almost exactly a year ago. Is that normal, or is that a death buzz?
  4. MrShorty

    MrShorty Moderator Staff Member 1000 Posts

    Hard to say without actually hearing the noise whether it is normal sounding or not. Best test would be a fuel pressure test. Since the problem seems to only be present at cold start, make sure you test the fuel pressure before a cold start.
  5. Naptime

    Naptime New Member

    I've often read these pumps like to be wet. Gas is expensive so lots of folks run around on empty, probably not the best way to promote a long pump life.

    Not saying it's your issue, just saying it may be something to consider.
  6. janikphoto

    janikphoto New Member

    Just off the top of my head, it sounds fuel-related. That narrows it down to pump, filter and injector(s)... Start with a pressure test, like the others suggested, as it should help narrow things down further.
  7. Pat10

    Pat10 New Member

    Thanks for the input, I did a pressure test today and got 60 psi key to on without start and 50 with it started.
    I think it was 60-66 with key on and anything 3-10 psi under that with engine on that my manual shows.
    But its still doing its of the line hesitation.
  8. Pikey

    Pikey Moderator Staff Member 1000 Posts

    Have you checked the fuel filter? You could have the pressure build up and show good on the gauge, but not have the flow when you first take off. When was the last time it was tuned up? plugs, wires? Did the problem start right after the intake manifold gasket was changed? If so then it may be sucking air. You can test that by spraying carb cleaner around the edges while it is idling, if the rpms go up then you found your leak. Also I would check the TB gasket with the same method.
    Last edited: Mar 30, 2012
  9. 99'HEARTBEAT

    99'HEARTBEAT Moderator Staff Member Platinum Contributor 1000 Posts

    x2.....on what Pikey has just mentioned above, and I'll add, when was the last time the Throttle Body-n-Injector's were Cleaned??
  10. Pat10

    Pat10 New Member

    I'm gonna look at the filter tomorrow, and as for tb ad injectors I've never cleaned them myself but I have run 2 Bottles of techtron through the tank.
    Here is a pic the week I bought it.

    Attached Files:

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