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Engine Trouble -- Need Advice

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by cleszkie, Feb 26, 2002.

  1. cleszkie

    cleszkie 1/2 ton status

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    Was driving to work this morning when my truck took a dump on me. Started up fine, drove about 4 miles and then felt it start missing and loosing power. When I stopped, the idle was very rough and then it wouldn't idle at all. I did manage to restart it a few times, but had to keep my foot on the gas to keep it running (rough). The exhaust now emits white-ish smoke-not steam. The truck had been running great up to this point

    Here is some background: '72 350 cid short block, Edelbrock Performer intake #2101, Edelbrock #1406 600 cfm carb, Mallory Unilite distributor. I just installed Edelbrock heat insulator gasket #9622 (I think thats the number) between the carb and the intake to eliminate fuel percolation. In the past few days, the engine has been "running on", or dieseling after it has been turned off which it never did before (it did this before I installed the heat insulator gasket). I have run the gas tank down very low a couple of times recently, so I thought that I might have sucked up something from the bottom of the tank and clogged a filter, but the symptoms don't seem to match. I have not had time to check the filters, distributor, carb, etc yet, so I cannot elaborate any more right now.

    ANY help, opinions, suggestions would be greatly appreciated.
     
  2. chevyracing

    chevyracing 1/2 ton status

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    Did you notice if the "smoke" smelled or not, like unburned fuel or antifreeze, or partially burned fuel.? Sounds like possibly a head gasket or the control module for the distibutor is not putting out enough juice. If you keep the rpm's up and it wants to run then maybe the advance on the ditributor is stuck. (the run on or dieseling is a hint to that)
    The first thing I would do to check is run a vaccume test then a compression test. That would give you a starting point to determine if it is electricle, fuel, or vacume. A very big mistake people make is they think if they have spark and fuel an engine will run, you need proper vacume.

    John

    Like to go sloppin' 'round in da mud in a rapid fashion....=)

    <a target="_blank" href=http://coloradok5.com/gallery/albun31?&page=1>BLAZER PICS</a>
     
  3. TopOff

    TopOff 1/2 ton status

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    This same thing happened to me when I first rebuilt my 383.

    Your Edelbrock has dirt in it. I found that you need to run the fuel injection type filters (or some filters that are just as good) with the edelbrock carbs. These carbs are VERY sensitive to dirt.

    I was using those clear glass and chrome type filters. I found these let small pieces of rust through and clogged my Edelbrock jets. I ended up pulling the carb off, cleaning it. Ifound small pieces of rust in the float bowls. I put it back on and it still ran like crap. Pulled it out again, blew out the jets and put it back on. It ran like a top again.

    Like yours mine was running great until I got the bottom of the tank.

    Good Luck.

    Roads, where we're going we don't need...roads. - Doc.
    '73 Blazer, 383 - 3/4 ton, ARB F&R, 35"
     
  4. ntaj*ep

    ntaj*ep 1/2 ton status

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    Hay bro, I agree with Chevyracing on this lets get a starting point. Take vaccum and comp. readings to see where your at. I think your unilite module took a crap (even took out your coil) but that is just, as they say SHOTGUN diagnosis!! Good luck let us know what is up.....

    The Red Beast
     
  5. cleszkie

    cleszkie 1/2 ton status

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    TopOff - Seems like you hit the nail on the head! I cleaned out the float bowls, jets, and all passages on the carb, and installed a new fuel filter (one for a fuel injected engine). Started the K5 up and its been running great since. Its amazing to find rust particles in the bowls even afterthe gas passes through two filters! Its even more amazing to see how sensitive the Edelbrock 1406 is to "dirt".
     
  6. ntaj*ep

    ntaj*ep 1/2 ton status

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    It's awsome to find the easy stuff, that dosn't cost much. It's even easer with these boards...I would have never looked at the carb first!! I wish I'd have found them sooner. Thats y you always need lots of friends to point you in the right (and not so right) directions. I always find stuff I would have never thought of, working on trucks, and talking with people!! Good call!!!

    The Red Beast
     
  7. chevyracing

    chevyracing 1/2 ton status

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    Did that stop the run on or dieseling?

    John

    Like to go sloppin' 'round in da mud in a rapid fashion....=)

    <a target="_blank" href=http://coloradok5.com/gallery/albun31?&page=1>BLAZER PICS</a>
     
  8. cleszkie

    cleszkie 1/2 ton status

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    Chevyracing -

    So far the truck has not dieseled once since I cleaned the carb. While cleaning the carb I also removed the distributor cap to check the cap and rotor for obvious damage, but found none. Very strange if you ask me. I am still going to run some diagnostics on the distributor to make sure that I didn't just temporarily fix my problem by jostling the distributor and wires around! Am also going to check the timing for correct advance. BTW.. what would you suggest for this setting? I think I'm at like 8 degrees right now.
     
  9. chevyracing

    chevyracing 1/2 ton status

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    Timing depends on your cam. I time with with my vacume gauge. Basically when I hit the max vacume it is timed. Around 8 degrees is usually okay.

    John

    Like to go sloppin' 'round in da mud in a rapid fashion....=)

    <a target="_blank" href=http://coloradok5.com/gallery/albun31?&page=1>BLAZER PICS</a>
     
  10. Steve_Chin

    Steve_Chin 1/2 ton status

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    The AFB and clones are sensitive to dirt. I can see where dirt might hang up the metering rods and prevent them from cutting off fuel supply under some load conditions. Glad you got it fixed.
     
  11. skyblazer

    skyblazer 1/2 ton status

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    That's interesting about the vacuum. When I installed mine, I had a conversation with the guys at MSD to determine where to start with initial timing and advance. They suggested 15* initial and the mechanical advance total is 36*, which was suggested by the head and cam manufacturers. I don't have any detonation under load, but I'd be interested to see how initial timing works out at max vacuum.

    <font color=blue>As my truck gets higher my balance gets lower!<font color=blue>[​IMG] <font color=red><a target="_blank" href=http://coloradok5.com/gallery/albuo72>PICS</a></font color=red>
     

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