99 gmc suburban stalls when warm

Discussion in 'Performance & Fuel' started by MrNc, Mar 12, 2010.

  1. MrNc

    MrNc New Member

    Hi have a 1999 GMC suburban 4x4 with 5.7L V8-350 vortec engine in August 2008 the fuel pump went out so i replace it with a airtex fuel pump in september i had to get the fuel drain ti ship it to germany. i picked it up in Nov. 45mins after driving the truck started stalling and died on the autobahn, after i wait about 10 mins it starts back up and drive for awhile i had it scan and it said i needed a new fuel filter, so i replaced it 30mins later the truck stalls again i put it in storage because i had to leave for iraq but now im back.
    Since ive been back i have replace cat. converter, spark plugs and wires, distributor, cap, rotor, 02 sensors, thermostat, MAF sensor everytime i replace one of these items the truck ran good for 30mins then stalls i replace all of these parts because the snap-on scan tool was picking up the trouble codes. i did a little research and found that unless you replace the pump with an ACDelco or a Delphi it will keep going out, i had a shop run a fuel pressuer test and they said it was of so i order a Delphi fuel pump and a new fuel pressuer regulator. do you think this will fix my probelm?

    also i hook my laptop up to my truck and the short/long term fuel on bank 3 and 4 is -45 sometimes getting as low as -101 bank 1&2 stays around 20 to 25.
    sorry for the long post trying to provide as much info as possible
  2. Gambit

    Gambit Rockstar 100 Posts

    I dont really think it is your fuel pump. I would check the Fuel Pressure Regualtor and Idle Air Control Valve. The IAC is a cheap replacement. The other thing i am thinking is if you are hooking up a lap top to your truck could you have messed with the ECM at all? Intentionally or not that could cause you alot of issues.
  3. Silverado Junkie

    Silverado Junkie Rockstar 4 Years 500 Posts

    My truck used to be sluggish on starting and didnt idle perfect even after changing plugs and plug wires so i took apart the idle air control valve and cleaned it, starts awesome and idles perfect now.
  4. MrNc

    MrNc New Member

    the shop called today they did another test the first gauge was bad it was only reading 40psi, today the reading was at 60psi but the fuel that runs back was really low. i dont think that the laptop messed with the ECM because the probelms was there before i ever used the laptop, i bought the scan tool because i was tired of paying the shop $40 bucks each time they did a scan.

    i have a new fuel pressure regulator on the way. does the IAC cause spark knock? I had to replace the intake gasket because the spark knock blew the old on off and i had a coolant leak
  5. Gambit

    Gambit Rockstar 100 Posts

    I wont tell you yes for certain but i will tellyou it is possible. The IAC will alter your timing to control your idle at cold temps. If it is bad it could be retaring your timing to the point of causing spark knock. Again this is reaching for an explanation on spark know that hard to blow a gasket. It wont hurt to replace a part that costs a few bucks.
  6. MrNc

    MrNc New Member

    ok i will order one and see what happens, maybe after i replace the fuel pressure regulator it will start working again I hope, haven't driven the truck for 2yrs now just in and out of the bay and it takes a week or 2 to get parts
  7. MrNc

    MrNc New Member

    the shop was talking about maybe replacing the map sensor

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