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running rich

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by 69K5, Jul 30, 2002.

  1. 69K5

    69K5 1/2 ton status

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    i have my .350 finished now and the new headers and mufflers installed. shes running rich though. its just black smoke. how do I (lean?) out the carb to stop this? she will die if i take my foot of the gas. as long its just barely pressed she runs, but as soon as i let it kick back fully she dies. i think shes flooding out due to the first problem. this is my first carbed vehicle so i need 3rd grade instructions for this one. this is a brand new (reman) q jet . arent they supposed to be preset? the idle screw is painted red and the jet screws are painted green if that helps.

    thanks in advance

    nathan
     
  2. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    Nathan,

    Sounds like too rich to me also. When you crack open the butterflies and get some air in there it runs OK, but without that air it just loads up with fuel.

    Do yourself a favor, check the fuel pressure before you invest too much time into carb tuning! I had a weird mechanical fuel pump condition where it had normal pressure for a while and then shot up to 20psi or so.....it took a while to locate that as the problem, and no amount of jetting or new carburetors will fix it.

    Now I have a new fuel pump and a pressure regulator, and life is good.
     
  3. 69K5

    69K5 1/2 ton status

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    Greg,

    How do I check the fuel pressure? And can i get a pressure regulator at the parts store?

    thanks

    nathan
     
  4. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    I don't know if it's a special gauge or what...the mechanic was the one that figured that one out.

    Pressure regulators should be available at local auto parts stores, or Summit-type places. The only suggestion is that you verify your fuel pressure FIRST! Don't use the regulator as a "band-aid" for a faulty fuel pump.

    And #1 caveat: Your problem may have nothing to do with the fuel pump or fuel pressure. I only mentioned it because on my truck, this issue gave me fits when none of the classic carb fixes worked. Specifically, turning the idle screws all the way IN (supposedly NO fuel entering the engine) and the engine continued to run fine.....
     
  5. 69K5

    69K5 1/2 ton status

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    Greg,

    thanks. i edidnt get to work on it last night so iwill tinker with it after church tonight. i will try adjusting the carb first , then if that doesnt work try the fuel pump route.

    thanks again

    nathan
     
  6. lizard

    lizard 1/2 ton status

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    Once you check your fuel pressure, check the engine vacume. Qjets have an enrichment circuit that activates below 8Hg. If your vacume is low at idle then the engine runs rich. GM has replacement springs to fine tune that but you can cut a coil or two off the stock spring.. just dont cut too much.

    BTW: What is the bore and stroke on a .350?
     
  7. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    I don't know what the bore and stroke are.....but I'll bet they're REALLY small....!!! LOL! /forums/images/icons/grin.gif
     
  8. 69K5

    69K5 1/2 ton status

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    ok this is getting to be a hassle. i took back the old carb b/c it was leaking due to a warped mounting plate. the new one runs fine w/o any problems. doesnt even run rich. BUT!!!! the little plunger thing on the front driver side that is connected to the accelerator rod (gas pedal) is spewing gas when its sitting there. i tried at idle and with some gas and it still leaks. i thought it might have been my spring holding something open , but moving it doesnt do anything? anyideas??

    thanks for the help

    nathan
     
  9. chulisohombre

    chulisohombre 1/2 ton status

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    it needs a new seal there at the plunger.or you can try and replace it again and hope for the best.
     
  10. 69K5

    69K5 1/2 ton status

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    well i tookit back and they said that i could just replace the seal. i told em i nknew that but i paid 100.00 for a working carb and not a rebuildable one. theres #4 on the way and will be here today. maybe this one will be good. well just wait and see, because patience is a virtue. #1 had a wraped base plate, #2 leaked out the plunger seal like a fountain, #3 had a vacuum port broken off and missing gaskets.

    nathan /forums/images/icons/confused.gif
     
  11. chulisohombre

    chulisohombre 1/2 ton status

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    hope fourth time is a charm /forums/images/icons/laugh.gif /forums/images/icons/laugh.gif
     

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