'90 Suburban R2500 7.4L (454) 2wd - Smokes on startup

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by stevehayes01, Oct 15, 2012.

  1. stevehayes01

    stevehayes01 New Member

    Hello everyone!

    So I got an issue with my '90 burb....if the truck sits for a few days I will get about 5-10 minutes of white smoke that smells like gas......after that the smell goes away until you start driving for a while then you get a bad exhaust smell like its running really rich.

    Truck specs and new parts:
    454 TBI (rebuilt 30K ago)
    2wd 3/4 Ton
    New Cap & Rotor
    New Plug wires
    New Plugs
    New Exhaust manifolds
    New Exhaust gaskets
    New Air filter
    New Fuel filter
    New O2 sensor
    new vacuum lines to the Evap canister
    New EGR valve --- After this change the truck runs very low idle and lopes...prior to swap it ran smooth but had a really bad odor from exhaust.

    So the things I have checked other than the replaced parts:
    Checked base timing w/est unplugged- Set for 6 deg. advanced
    Checked all vacuum lines
    Checked injectors w/timing light - spray pattern is rough but even

    So now I am not sure what to look at...... The only other things I can think of are the MAP, IAC and TPS...but not sure. Any help is appreciated.
  2. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    Is it losing oil? the oil could be leaking down the valve seals and into the cylinders while it sits. I don't think that it would give you 10 minutes of smoke though.
  3. stevehayes01

    stevehayes01 New Member

    Oil is doing ok..... small leak in the oil cooler but nothing major. This really smells like fuel for the most part like its got a fuel leak in the injectors dripping into the heads.
  4. oldmanstruck

    oldmanstruck Rockstar 100 Posts

    are you losing coolant? My 88 had a bad intake manifold gasket. So every morning, it has lot's of white smoke, kind of like you drive it in the COLD day but once it warm up, smoke goes away. Didn't have strong odor or smell though...
  5. stevehayes01

    stevehayes01 New Member

    Topping off coolant every 6-8 weeks. But not too much.

    Did you have a sweet smell in the exhaust at all?
  6. oldmanstruck

    oldmanstruck Rockstar 100 Posts

    even though I knew my intake manifold had a leak. I check my coolant, color looks good, exhaust didn't really have the "sweet" coolant smell. But I check closely near the intake I could see wet surface.
    I used a couple stop leak and no more sign of leak near the intake but I still have the morning white smoke for about 10 minutes or so
  7. wulk025

    wulk025 New Member

    White smoke = coolant - Blue smoke = oil - Black smoke =gas.
    Also check your spark plugs for fouling as you will be able to use the spark plug chart to determine what fluids are getting into your combustion chamber.
    Last edited: Oct 17, 2012

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