Hard Starting 99

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by Fast Al, Oct 13, 2008.

  1. Fast Al

    Fast Al New Member

    I have a 99 k1500 Suburban 4 wheel drive with 135,000 miles. I have a very hard start problem, i have replaced the fuel filter, fuel pressure regulator, plugs, wires and my buddy did a fuel injector balance test and they were all good. I had codes of p0171 and p0174 which is misfire and it said to do the fuel injector balance test which we did and was ok, the fuel pump puts out 60 psi at start up and 50 psi while running. When i get it started it runs great with no problems. Any ideas on what to do next?
     
  2. dwill3015

    dwill3015 Epic Member 5+ Years ROTM Winner 1000 Posts

    Welcome to the site! There are a few memebers here with late 90's Burbans that I'm sure will help you out.
     
  3. GaryL

    GaryL Epic Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    You said you replace the plugs and wires, did you replace the cap and rotor as well. Might also have the ignition control module checked.
     
  4. Fast Al

    Fast Al New Member

    Yes i did the cap and rotor when i did the intake gaskets. I have not checked the ignition control module. Is the module located by the coil? How do you check the module?
     
  5. GaryL

    GaryL Epic Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    Yes, it is by the coil. I'm not sure where you are, but the Oreilly Auto parts stores around here will check them for you.
     
  6. Fast Al

    Fast Al New Member

    I have Checker and O'Reily by me. I will call them and see if they can check it. Thank you for the info.
     
  7. Fast Al

    Fast Al New Member

    I took the ignition module in last night and had it tested and they said it was good. Any more ideas on what it could be.
     
  8. MrShorty

    MrShorty Epic Member Staff Member 5+ Years 1000 Posts

    According to my code list, those codes are O2 sensor indicates lean codes rather than misfire codes. Any sign of a vacuum leak? Fuel pressure looks normal. Is the fuel pressure coming up immediately, or does it take a few tries before the pressure comes up? How quickly does the fuel pressure bleed off when the pump shuts off? Any sign of fuel in the intake (indicates the FPR is leaking)?
     
  9. Fast Al

    Fast Al New Member

    Yes pressure comes up the first try. Pressure does not bleed down. I just replaced the fuel pressure regulator. I get those codes for the o2 sensors only when it starts hard. I have the code #'s at home for the misfire.
     
  10. MrShorty

    MrShorty Epic Member Staff Member 5+ Years 1000 Posts

    So it sometimes starts normally? If it is intermittent, did you check fuel pressure when it was hard to start, or did it start normally when you checked the fuel pressure?

    I had an intermittent hard start/stall/rough running condition earlier this summer. I would sometimes get misfire codes and lean codes. Turned out to be a loose battery post. I guess the randomly varying supply voltage caused the engine management system all kinds of problems. I would suggest checking the battery cables, and other electrical components to make sure there isn't a loose connection somewhere.
     

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