Hard start after driving?

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by NagRuTan, Jun 20, 2012.

  1. NagRuTan

    NagRuTan Rockstar


    Got a buddy that has a bone stock 99 2500 with about 140k. He's got a problem with hard starting. First thing that popped into my head was a search here and found some info about the bad fuel pumps and fuel regulator. But from the descriptions in these threads it looks like a completely different problem. Here is the description.

    • burb fires up fine on the first touch of the key in the morning.
    • after driving for say 25-30 mins and parking, it takes 3 hits with the key before it will start again or one long hit with the key (30 secs or so).
    • if the burb sits for an hour or more it will start up with one hit of the key.
    • fuel pressure tests good
    • no fuel smell
    • has been doing it for the last year
    • just had a tune up and still does it
    • no performance issues beyond the whole hard start

    Any ideas people?

  2. moogvo

    moogvo Epic Member 5+ Years 1000 Posts

    you might do a back pressure test to see if the cat is clogged. You can also check the temp of each end of the cat if you have an IR thermometer gun. There should be no more than a 400 degree difference from front to back. Does it lack power when it gets warm too?
  3. NagRuTan

    NagRuTan Rockstar


    No issues at all besides the starting, and no power loss issues (runs great). Also the entire exhaust was replace less then 4 months ago. I hooked up my scanner and no codes are popped. I was thinking crank sensor.

  4. MrShorty

    MrShorty Epic Member 5+ Years 1000 Posts

    One of my first thoughts with a hard warm start like that is a bad fuel pressure regulator. When you say there was no fuel smell, were you referring to the vacuum line coming off of the FPR? If not, next time you run the engine, disconnect the vacuum line and see if there is any gas coming out of the vacuum port on the FPR.

    Along the same lines, one or more "leaky" injectors could do a similar thing. When you tested the fuel pressure, did you include a "leakdown" test where you watch the pressure for several minutes after the pump shuts off?
  5. NagRuTan

    NagRuTan Rockstar


    I will check the fpr for fuel when i see him at work. The fuel pressure and leakdown are well within tolerance.

  6. RallySTX

    RallySTX Member 100 Posts

    Check for spark when this happens, and examine the air intake system for issues. I would give the engine a compression test, cold engine, all plugs out, watch for pump up while cranking. If this truck has a snorkel with the hot air diverter, or stovepipe, check it for correct operation. Try depressing the throttle when hot cranking to see if mabye it isn't getting enough fuel or air to fire up.Remove the gas filler cap and listen for air rushing into the tank, or tank noises. Runit with the cap barely on or loose to determine if a vacume is being created there.
    Brian L.

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