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.

backfires thru carb

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Kodiak, Jun 6, 2000.

  1. Kodiak

    Kodiak 1/2 ton status

    Joined:
    Mar 17, 2000
    Posts:
    178
    Likes Received:
    0
    Location:
    Kodiak Island, Alaska (the emerald isle)
    Heres the problem. When I get in my blazer in the mornings I have to accelerate slowly or the motor backfires thru the carb. A little gas and it runs fine but alot and it backfires. When it is warmed up it doesn't do it as often. Other times I can stomp it and the thing kicks in like it is suposed to. I have a 350 with a 4bl quad. Whats causing it and how do I fix it.
     
  2. bablazer73

    bablazer73 1/2 ton status

    Joined:
    Apr 4, 2000
    Posts:
    3,363
    Likes Received:
    0
    Location:
    upstate ny
    check your ignition timing. make sure the vacuum advance and mechanical advance work. is it a fire backfire? or a "dry fart"(no flames)

    your right. I don't understand the jeep thing!
     
  3. dumbfounded

    dumbfounded 1/2 ton status

    Joined:
    May 20, 2000
    Posts:
    176
    Likes Received:
    0
    Location:
    Castalia, NC
    I agree check your timing. Things like this are usually simple the hard part is finding them. A slipped timing chain can cause backfires but the engine usually won't run good or at all and it doesn't fix itself, so stick with the timing. Make sure all your vacuum hoses are hooked up and also check them for cracks. Carb cleaner sprayed on the hoses, carb, and intake is the quick way. Listen for the motor to speed up if it does there's a leak if it doesn't either there isn't a leak or it isn't big. One more thing check your plug wires I had the same thing happen and it drove me nuts it would run fine but sometimes it would go nuts especially under acceleration. It ended up being a plug wire burned on the exhause and when the motor was twisting under acceleration it was sparking on the wire not the plug. So try a regular tune up if you can't find it...

    Wasn't me.............
     
  4. MA87K5

    MA87K5 1/2 ton status

    Joined:
    Apr 6, 2000
    Posts:
    558
    Likes Received:
    0
    Location:
    Chicopee, Ma 01020
    Also check your cam itself some lobes might be worn. I had the same problem and it turned out to be a bad cam. Check by removing the valve covers and running the engine and looking at the lifters to see if they all move the same distance. If some move more then the others then there is your problem. Just hope it isn't that. But if it is, change the timing chain at the same time.
     
  5. Kodiak

    Kodiak 1/2 ton status

    Joined:
    Mar 17, 2000
    Posts:
    178
    Likes Received:
    0
    Location:
    Kodiak Island, Alaska (the emerald isle)
    Why does it do it more when the motor is cold. It has had a tuneup (new plugs,wires,dist cap,rotor) and the carb was rebuilt. It didn't change anything. Also it doesn't do it all the time. It will run for a week without a backfire and then all of a sudden any gas at all causes a backfire. I guess it is dry as aposed to fire. Don't really know because i'm not going to stick my head under the hood while its doing it.
     
  6. mudfanatic

    mudfanatic 1/2 ton status

    Joined:
    Feb 18, 2000
    Posts:
    614
    Likes Received:
    0
    Location:
    Aloha, Oregon
    I just changed the Cam in my rig, it had 2 flat lobes and 3 badly worn lobes, that solved some of my backfiring problem but not all of it. I thought that all of my vacuum lines were fine but when I went underneath to change the oil I noteced that the vacuum line at the back of the tranny was loose, I shoved that on tight and eliminated the kink in it and now my rig is running great again except for the flat spot off the line while it's cold.
    Dan

    <font color=red>get involved with land issues or lose the land</font color=red>
     

Share This Page