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88 k5 crankcase and idle problems

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by jwill, Dec 23, 2004.

  1. jwill

    jwill Registered Member

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    Howdy again everyone. Again problems with my 88 k5 daily driver. so I start up the truck this morning and after about 5minutes of ideling I drop her into drive and head out of the drive and down to the end of the block to fill up. she starts to stumble really bad at idle. so I pull in fast to get some gas figuring that the truck is really out of gas since i was burried on E. Well i filled up and then it does it again when pulling out..In gear or sometimes when out of gear the stumble is still there. its actually bad enought to think that the timing is off but when she starts up and you rev her she is clean. really revs nice and once in a while will stumble around during a rev. My guess is that its a bad TPS sensor and ive gotten one from work. While I was under the hood I checked fluids all looks good but when I took off the oil fill cap and gave it a sniff it smelled of fuel. My guess is a bad PCV valve. ANY help would be greatly appriciated.
    THANKS fellow K5ers

    Jwill....IA
     
  2. 84mudmachine

    84mudmachine 1/2 ton status

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    I had a simular problem

    Mine would warm up nice and then I would go out and drive it about a block and then it would want to die and idel bad. I worked on the carb for a few days and never could get it to run just right(durring the summer it ran fine). I ended up taking it to the shop, and found out the ignition system in it was not the setup I needed. It was the original, but since the po put in the new motor and never hooked up any of the sensors, it would adjust the timing and really mess things up. The shop put in an early 80's ingition system that does not require the sensors and that took care of my problem. They also adjusted the carb and choke, that was way off.
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    Hook it up to a scanner, see what O2 readings look like, among other things.

    Not real familiar with overfueling, but I suspect if you are running pig-rich, it will contaminate the oil. No other way for fuel to get in oil on an electric fuel pump vehicle I can think of, short of a leak from the intake into the block.
     
  4. jwill

    jwill Registered Member

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    THANKYOU both for the help. Ive been racking my brain all day..This is my only driver for the winter. And with money so very tight im looking for the most cost effective way of fixing this without going to a cheaper part line. Even with my employee discount at work....parts are killing me :( My first guess was a throttle posistion sensor. And Im hoping that is what it really is. The fuel smell in the crankcase, could a clogged or plugged PCV valve be a option?

    Jwill...IA
     
  5. imiceman44

    imiceman44 1 ton status

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    Like dorian said check that O2.
    Next check your distributor.
    The shafts are known to wear out and start wobbling and my friend just went through the same problems and it got worse before we found the culprit.
    At the end it would stumble and die every stop.
    Now the third and maybe easiest fix might be a clogged fuel filter because you let it go too deep in the reserve and sucked all the crap out.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Some places (I thought autozone?) used to let you borrow a scanner.

    TPS is one of the things you can check with it, no reason to replace good parts. It doesn't take long of throwing parts at a problem where a scanner would have been cheaper to buy anyways.
     
  7. jwill

    jwill Registered Member

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    Thanks again. The truck currently has no o2 sensors due to the po removing the AIR pump and adding a cheap dual exhaust system(now replaced). Im not thinking that it would be the Dist. It just started this morning and last night she ran like a top. Just like it has for weeks and suddenly it just started this. The fuel filter is less than two months old its a Napa gold(as are all my filters). Maybe i did run it too deep and sucked up some bad stuff. The truck has been down here from Montana for a few years now and has been run on ethanol. Which is highly known for its very corrosive effects on the fuel system. Im still not sure why the crankcase would smell like fuel yet. Tomorrow ill head down to work for a chance at using our scan tools. The 350 is in good shape and good power for the 85k that it has on it. moves my 3:08 geared 33inch k5 around quite nicely.

    Jwill...IA
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    Has it been converted to a carb?

    No O2 (only one on these trucks) means its running in limp mode if it's the factory TBI, which will be rich.
     
  9. jwill

    jwill Registered Member

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    No its still TBI. Im pretty sure there are no o2 sensors being used due to the lack of cats since the new exhaust. Due to the -15 degree temps last night I wasnt able to be under the hood for long looking for some o2 sensor blockoffs or deletes like we sell at work. The removal of the AIR pump and cats was actually pretty quality work and the truck has up till yesterday morning ran perfectly and not really used that much gas. So ive never thought that it might be running rich at all. Im going to try to get down to work later on today to use our scan tools.
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    O2 has nothing to do with cats.

    If it's missing the O2, it's not running right, whether it feels like it or not, period.

    I wouldn't waste time looking at ANYTHING else if there is no O2 between the head and the tip of the exhaust pipe.
     
  11. jwill

    jwill Registered Member

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    SORRY everyone. I was thinking that the o2 was in the Y pipe because all of our diagrams at work show it as being there...Its in the Left manifold is where I am thinking. I will be pulling it off today to check it then also the fuel filter Because I may have sucked some trash up into it by running the tank so low the last few times Ive filled up.

    Jwill...IA
     

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