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Hesitation periodically at 30 and up MPH

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by txguy, Apr 15, 2002.

  1. txguy

    txguy 1/2 ton status

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    Everyone, a little help please. I have replaced the plugs, wires, cap, rotor... The problem first started when I was on my way back from the slab. At highway speed it started hesitating/bogging down. More gas did not help. Downshifting sometimes helped. It seemed that if I let off the gas a little the power came back up a good bit, or back to normal. Also, since this has started, sometimes it it very hard to start after it is hot. I have advanced the timing some, and it has improved, but is still behaving in this manner. It does not seem to do this unless it has been drove for at least 30 mins, or longer.

    Any ideas? The next thing I am going to do, is replace all the vacuum hoses. I thought it may be the tranny going out, but the engine does not speed up like it is slipping. If feels like the power is just gone all of a sudden.

    Tony
     
  2. Sounds like a low fuel delivery problem? Check your fuel filter, sounds like lack of fuel. I had a fuel pump go out on a chevy swb and I limped it home at 35 mph one night. Make sure your fuel filter isn't plugged and see if you have fuel pressure.
     
  3. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Is your truck carbed or FI?
     
  4. txguy

    txguy 1/2 ton status

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    Sorry, Carb... Wish it was a FI! I will check the fuel filter. I changed it about 3 months ago.
     
  5. Thunder

    Thunder 3/4 ton status

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    If the fuel system turnes out to be ok and the problem still happens. It may be the Pickup coil or the module in the distributor.
    You said it happens after you have driven a while and it is good and warmed up.
    If the module or pick up coil are going bad, they will often start crapping out after they get hot and too much resistance builds up in them.
    You can take the module down to an auto parts store like Napa or Checker and have it tested to see if its good. They hook it up to a meter and put a heat gun on them to see if they fail.
     
  6. txguy

    txguy 1/2 ton status

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    UPDATE. Now its doing it 5 mins after starting! I am think the fuel delivery sounds like the next logical step. Aren't there a few diff types of fuel pumps I can resolve this with? Don't some sit in the tank, and others are outboard?
     
  7. lukerz

    lukerz 1/2 ton status

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    I changed the filter right at the carb and this similar problem went away (84 chevy van 305) My problem was mostly under load (up hill hesitations, higher speeds) I did wires, plugs, cap and rotor as well. Hope this helps.
    Luke
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    It sounds like it *could* be a cat converter problem as well.
     
  9. k5ntexas

    k5ntexas 1/2 ton status

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    this same thing happened to me not too long ago and it was my fuel pump going out. it did the same exact thing that u mentioned. i also had a crimp in my fuel line right near the where the fuel line goes into the carb and that didn't help anything either. just check the fuel pump if its puttin fuel out or anything. there are two ways i know of to check the fuel pump. try putting an inline fuel filter. a clear one to see if yer gettin enough fuel. if its full then you are getting enough fuel. if its not then you aren't and it may be the fuel pump. another way to check is to take the fuel line off and turn yer engine over and see if gas comes out of it. well i hope this helps. oh and btw a fuel pump cots only about 19.99 at oreilleys or however that place is spelled. again hope it helps. later.

    jacob
     

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