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89 K1500 Runs rich.

Discussion in 'Chevy Trucks' started by rollsroyce1999, Aug 25, 2004.

  1. rollsroyce1999

    rollsroyce1999 Junior Member
    from Ohio
    Messages: 6

    Hey, I have a question. I have an '89 K1500 w/5.7L. The truck starts and runs ok, however it is running waaay to rich. When you look in the T-body, it is pooring the gas in (at least it seems like more gas than my dads '88 5.7L burb). The other give-away's are; it idles at like 1100 w/ the set screw backed all the way off, and it runs doggy. I have already replaced the regulator and that didn't do the trick. Has anyone else had a problem like this? I hope someone can help, the gas mileage is killing me.
  2. rollsroyce1999

    rollsroyce1999 Junior Member
    from Ohio
    Messages: 6

    Ok, so here's the deal. When I got this truck it didn't run very well, but I figured after replacing the cracked distributer cap, advancing the ******** timing and replacing the horrible exhaust it would liven up. At this time I didn't notice the idle speed problem, but I did have suspicions of the following:
    The guy I got the truck from told me that the motor had been swapped, I was concerned that a 305 was put in place of the 350 ( since they are nearly identicle outside except for the casting numbers). Unfortunately I was not able to clearly read the casting numbers on the back of the block, and my friend (who is basically a chilton's manual for chevy's) told me he was sure it was fine. I wasn't convinced but ended up getting the truck anyways (it was still a good deal).
    Last night I was finally able to get a visual of the casting number. I bet everyone can guess what it read.

    Hint: not 5.7L

    So now I need to find out which pcm it has, and if the throttle-body, or any other important stuff was swapped off of the 350 onto this motor.
    I know this truck came with the 350 originally because it has K's in the vin number.
    So my next question is, is there anyone who plows with a 305 truck? I've got a 7' Meyer and a huge brush guard.

    Thanks and sorry this message is so long.

  3. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    There has been a 'temporary' 305 (carb motor) in my one-ton dually for the past 4-5 years now. It plows fine, even pulling around the truck (10000lbs plus with plow and ballast, 7000+ empty) though it will certainly not win any races and the long uphills are problematically slow. I think mine does so well because it has 4.56 gears.... but in a half-ton it should work just fine.

    You can either replace the motor with a proper 350, or find a wrecker computer PROM from a 305 truck... pretty sure the throttle body and injectors is identical.

    Very quick and easy to fix as long as all the sensors are working.