Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

air intake to TBI

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BigGray89Blazer, Oct 5, 2000.

  1. BigGray89Blazer

    BigGray89Blazer Registered Member

    Joined:
    Sep 27, 2000
    Posts:
    6
    Likes Received:
    0
    having so engine issues if anyone has some input it would be greatly appreciated. ok, engine seems to stall on me. I take the air filter off and and filter arm and run the engine. As the engine runs (with air filter off) it will start to idel rough. At that point the engine will suck a huge amount of air in and then idel ok, with proceedure repeating itself. could it be a sensor that is not working correctly with the calculation of air and gas mixture. Also when I put the filter on the engine it will (all of this while in park) run rough and stall. this is an 89 350 5.7 TBI engine. could it be the mass air flow sensor??
     
  2. 90K5

    90K5 1/2 ton status

    Joined:
    Jun 1, 2000
    Posts:
    3,719
    Likes Received:
    0
    Location:
    Lubbock, TX
    Try replacing your fuel filter. When they get old and plugged up they make it stall. If that doesn't do it it might be the fuel pump. I dont anything know about the mass air flow sensor though.

    90K5
     
  3. jarheadk5

    jarheadk5 1/2 ton status

    Joined:
    Mar 6, 2000
    Posts:
    4,389
    Likes Received:
    0
    Location:
    PA
    I don't think the 89 had a mass-air setup, I think it was a manifold-absolute-pressure (MAP) sensor setup. If the oxygen sensor hasn't been changed recently, a new one could help.

    [​IMG] Semper Maintenance!
     
  4. bart

    bart Registered Member

    Joined:
    Mar 15, 2000
    Posts:
    69
    Likes Received:
    0
    Location:
    Eastern PA
    your 89 350 tbi has a Manifold Air Pressure Sensor...it is connected to the back of the TBI unit it the middle. It is rectangular and has a 3-pin connector on it. If this hose is off or cracked, you will experience a very rough and unstable idle. Check this line for a problem.
    Did your check engine light come on? If so, read the code by shorting the B pin of the ALDL connector to ground...it's the second one in on the top right of the connector under the dash near your right knee...it will flash "12" three times, and then the trouble code...
    If not, check the Idle Air Control on the passenger rear side of the TBI...it could be malfunctioning.
    Look for the obvious first...broken lines, etc.

    bart
     
  5. realsquash

    realsquash 1/2 ton status

    Joined:
    Jul 12, 2000
    Posts:
    778
    Likes Received:
    0
    Location:
    SE WI
  6. archer

    archer 1/2 ton status

    Joined:
    Aug 17, 2000
    Posts:
    136
    Likes Received:
    0
    Location:
    tn
    Yea, the iac motor is responsible for adjusting idle proportionate to load, when the ac kicks in, under electrical load etc.. that's a likeley suspect. You should also check for false air, air getting in beyond where it is metered (mass air flow sensor or throttle body) You shouldn't have a maf sensor (as stated) but if your throttle body bolts are even a little loose this will do it. You probably won't even get a code from the mil light. If you do it'll probably be irroneous, like an oxygen sensor code, or TPS code. remove the throttle body, clean it well then place a new gasket under it and tighten the bolts to 18-20 ft. lbs. You may also check to see if the rod that holds the butterflys over the throttle bore haven't rounded out a bigger hole where they fit into the throttle body. These are all common problems in that year model.

    "who dares wins"
     

Share This Page