99 sts running rich
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Northstar Engines and System Technical Discussion Discussion, 99 sts running rich in Cadillac Engine Technical Discussion; i have a 99 sts that is running extramly rich when i start it up it will kick out a ...
  1. #1
    stslv is offline Cadillac Owners Member
    Automobile(s): 99 sts
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    99 sts running rich

    i have a 99 sts that is running extramly rich when i start it up it will kick out a cloud of white exhaust that smells like gas,will also do that when accelartion from lights. have been searching site an from what i have read it looks like a plenum leak could it be anything else were should i also look

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  3. #2
    Submariner409's Avatar
    Submariner409 is offline If it won't run, stick on fender vents
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    Re: 99 sts running rich

    Remove the engine cover. Locate the Fuel Pressure Regulator on the rear of the fuel rail. Vacuum hose to the throttlebody.

    Start the car and pull the vacuum hose off the regulator nipple. Raw gas in there ?? New regulator time.

    www.rockauto.com

    Use a stethoscope to listen to each injector for a steady "tick-tick-tick-tick". If one sounds erratic or not at all, stuck injector. Junkyard or rockauto.

    Air filter and throttlebody cleaning time ?

  4. #3
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
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    Re: 99 sts running rich

    have been searching site an from what i have read it looks like a plenum leak
    A plenum leak would cause it to run lean. Your '99 does not have a "plenum" (rubber coupler between the TB and the manifold). That came in 2000. Follow Subs advice.

  5. #4
    stslv is offline Cadillac Owners Member
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    Thread Starter

    Re: 99 sts running rich

    thaks sub just checked it gas pouring out will get replacemnt and replace it. let you know how it works

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