what could cause this???

Discussion in 'GM Powertrain' started by ChrisZ71, Jan 20, 2011.

  1. ChrisZ71

    ChrisZ71 New Member

    I have a 91 z71. Whenever I start it up it cuts off on me. Kinda like its choking down. I have to press the gas for about 15 seconds then it runs and idles like its new! It will only do this if it sits for more than a few hours. If I go into someplace and spend about 30 minutes and come back out it starts up without any problems. What could be causing this?
  2. ntbush83

    ntbush83 Epic Member 5+ Years ROTM Winner 1000 Posts

    That is pretty weird. What comes to mind for me is maybe a fuel line is leaking and your losing pressure at start up but when you pump gas back into the fuel system its fine and when driving its a small enough crack it doesn't affect fuel flow. I may be wrong.
  3. R3dn3ck

    R3dn3ck Member

    go get a fuel pressure test and see how it goes if nothing then check and clean your carb
  4. ScubaSteveo

    ScubaSteveo New Member

    sounds like a fuel pressure regulator to me.
  5. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    Also just so you know Rd3n3ck the 1987 up models came with EFI, and Throttle body with the built in fuel pressure regulator. No carbs to tune anymore on them. Not to be rude just letting you know since i thought they were carbed as well before i got one.
  6. R3dn3ck

    R3dn3ck Member

    no no its cool im used to carbs and gettin used to thorttle
  7. R3dn3ck

    R3dn3ck Member

    rebuildit it, put new TPS on it and its still actin up. You can have the throttle wide open in park but you put it in gear it wont step up
  8. Ethan

    Ethan Rockstar 100 Posts

    Haha, my truck was doing the same thing, cleaned it and it fixed it, but the EGR valve was stuck open, so it would pump EGR gas into the throttle body during start up and choke it out. Try replacing your EGR valve and cleaning all your EGR lines.
  9. daddytech

    daddytech Epic Member 5+ Years 500 Posts

    Seafoam always worked well for me, i take the main vacuum line out of the power brake booster let it suck all the seafoam from the can and lightly rev till the smoke stops and then i am good to go, fill the tank with gas then put another can in there and my tahoe stays running like a champ for a while after that. not a suggestion but that's what i do
  10. Johnny_Buchanan

    Johnny_Buchanan Rockstar 100 Posts

    Dunno if it applies here, but one possible cause could be weak battery. My Caddy had a similar problem and that went away when new battery went in.
    Does it crank ok?


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