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.

Hesitation going fast

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by beachinblazer, Apr 27, 2002.

  1. beachinblazer

    beachinblazer Registered Member

    Joined:
    Apr 15, 2002
    Posts:
    20
    Likes Received:
    0
    I've got an 86 K5 with 305 in it. It recently has begun to hesitate badly at higher RPMs. I rebuilt the distributor, so everything is new there. The timing is set 8 BTDC and with the vacuum applied its runs great. The only problem is whenever it sees higher RPMs (not sure when exactly) it misses and hesitates badly. Also, in 3rd (700r4 tranny) going about 45mph into the wind is about the most it can do without missing. Anyone know what might be the problem?
     
  2. Thunder

    Thunder 3/4 ton status

    Joined:
    Jul 20, 2000
    Posts:
    8,946
    Likes Received:
    1
    Location:
    Northeast Nevada
    How long has it been sence the fuel filter has been replaced. It may be clogged and starving your engine for fuel at higher RPMs.
    Are you FI or Carbed?
     
  3. bklynlifted

    bklynlifted 1/2 ton status

    Joined:
    Feb 4, 2002
    Posts:
    261
    Likes Received:
    0
    Location:
    brooklyn ny home of the brave
    CARB OR FUEL INJECTION EITHER WAY IT SOUNDS LIKE A FUEL RESTRICTION PROBLEM. CHECK YOUR FUEL DELIVERY SYSTEM. DOES THIS HAPPEN ONLY UNDER A LOAD OR WHEN STANDING STILL AND REVING IT UP. PS FILL OUT YOUR VEHICLE PROFILE FOR A MORE ACCURATE RESPONSE . GOOD LUCK
     
  4. beachinblazer

    beachinblazer Registered Member

    Joined:
    Apr 15, 2002
    Posts:
    20
    Likes Received:
    0
    i've already checked the fuel filter. you think a fuel pump is good for almost 170,000 miles? if not then thats probably my problem. It really only happens under load (going up hill or into the wind)
     
  5. Thunder

    Thunder 3/4 ton status

    Joined:
    Jul 20, 2000
    Posts:
    8,946
    Likes Received:
    1
    Location:
    Northeast Nevada
    Yeah it could be the pump. The symptoms sound like it. After 170K miles it's probabally getting weak.
     
  6. k5ntexas

    k5ntexas 1/2 ton status

    Joined:
    Oct 29, 2001
    Posts:
    2,517
    Likes Received:
    0
    Location:
    corpus christi, texas.
    yeah its the pump. the same thing happened to me a few weeks ago. replaced it and it ran much better. i also had a crimp in my fuel line right where it goes into my fuel filter into the carb. it was a bad crimp. but the fuel pump was a gonner cuss we put a clear inline fuel filter and we had not much gas. so just replace the fuel pump and most likely that will be it. hope this helps. later.

    jacob
     
  7. MudNurI

    MudNurI 1/2 ton status

    Joined:
    Jul 15, 2001
    Posts:
    2,113
    Likes Received:
    0
    Location:
    VT
    Im suprised nobody mentioned this--

    a cracked spark plug will cause the same problems. our 89 was running horribly- but only when you got after it, almost puking..etc.. brought it in- they changed the fuel filter, no better, brought it back, they changed the plugs- said one was cracked, no better- brought it back- they had cracked a different one, they replaced it and to this day- running like a charm, with over 400K miles on it, driven every day...check the little stuff- before you go replacing the pump...

    Brandy
     
  8. Can Can

    Can Can Pusher Man Staff Member Super Moderator

    Joined:
    Feb 17, 2000
    Posts:
    15,552
    Likes Received:
    136
    Location:
    Cochrane, Alberta, Canada
    And a bad wire can cause the same thing, too. I wouldn't rule out an ignition problem.
     

Share This Page