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Pinging/dieseling under full throttle

Discussion in 'Trucks and Trailers' started by JCurtis, Jan 8, 2001.

  1. JCurtis

    JCurtis LawnSite Senior Member
    Messages: 292

    Have a 86 chevy K10 with 305 during the last snow storm it began running rough, stumbling and stalling at traffic lights.

    I know its not the gas as I use the same gas in my car. I had the carb taken off, cleaned, adjusted etc. also changed plugs wires etc. Still rrunning rough!!!

    Ran it yesterday in the yard, with a little pressure on the pedal. Noticed a lot of what seems like Carbon deposits on the snow about two feet from the exhaust.

    My question is, Could a carbon buildup in the combustion chambers cause this rough running. Also is there any way to clean out the carbon. I seem to remember an old mechanic drizzling a little water down the carb of a vehicle a long time ago to clean out the carbon. Anyone ever tried this?

    Any other suggestions???
  2. 85w/350

    85w/350 LawnSite Member
    Messages: 244

    I have never heard of water being poured down....I'd say just run a good engine treatment and if you are dedicated enough pull the ting apart and soak everything really well in cleaners....sounds strange though because I would have guessed it was running rich but if it was all recently adjusted and tuned it shouldnt be...back to water...maybe it wouldnt hurt I've poured tanny fluid down mine to look for exhaust leaks...granted that was just a capfull...which I doubt would help much as far as water cleaning things in your situation.
  3. Fierospeeder

    Fierospeeder LawnSite Member
    Messages: 51

    Try checking the timing.

    Also, if you have a carbon buildup, it will cause you to have a higher compression and make you start pinging.

    Try going to your automotive store and look for carbon cleaner, i know there is some product that you can pour down the carb, and you have to hold it at full throttle so it doesn't die out. NOTE Also you have to beware that it doesn't backfire in your face.
  4. John DiMartino

    John DiMartino LawnSite Silver Member
    Messages: 2,555

    pull the distributor cap off,check for moisture,and especially carbon tracking.If there is any replace the cap and rotor,if there's to much carbon the spark can jump to the cyl next to the one thats supposed to fire,giving you a nasty ping since that cyl isnt in proper position to be ignited.
  5. yardsmith

    yardsmith LawnSite Senior Member
    from Ohio
    Messages: 628

    dittos to other advice here.
    Take the cap off to see if it has buildup on the terminals; if so, replace the cap.
    Also it sounds like a timing issue. If your clamp bolt isn't tight, it can work loose & the distributor can turn slightly, making it out of sync. If you've had a backfire, it can throw your timing off too.
    I have/still do the water in the carb trick. It helps clean out residue & has the effect of "steam cleaning". Don't do it all the time, however. You gotta keep one hand revving at mid rpm & higher so it doesn't stall. Pour the water steadily; don't dump it all at once. I usually do it when I buy a used vehicle if the carb is filthy, in addition to a carb cleaner & toothbrush scrubbing.
    There are alot of good products out there you pour in the tank to clean injectors with & such; try them also.
  6. John DiMartino

    John DiMartino LawnSite Silver Member
    Messages: 2,555

    I do the water in carb trick too,but i rig up a vacuum hose to the intake and put a couple of gallon jugs in the pass side floor,run the vacuum line into the cab,and i restrict it by putting a kink in it,like you would a garden hose.I do this when we are going somewhere.once we get on the highway,i open the line and put it in the first jug and let it suck water,a little at firts,giving it more until you have to give it more throttle to maintain speed.I try to keep it at that point which seems to be about a gallon to 10 miles.After 3-5 gallons of this i head home,drop the oil+ filter,since some water always ends up in there.does it do anything?I think so,if anyone has ever replaced a blown headgasket on a car that has been driven even only 10 miles,they will see the cyl that blew is steam cleaned while the rest are carbon covered.You get nice smoke for a few minutes when doing this.i dont know if i can damage anyhting,other than maybe an Oxygen sensor,but inever have done any damage that i know of.The truck always ran better after that.
  7. mstyles0927

    mstyles0927 LawnSite Member
    from SC
    Messages: 32

    I have seen the water trick before--I was always told to let the water flow in no faster than you could drink it--a little is better than a lot.

    Another trick I got from an 'old-time' mechanic is to remove the PCV connection from the valve cover and let it suck a couple capfuls of automatic transmission or power steering fluid into the intake manifold (works like a shop vac). This again hits carbon deposits (cool liquid vs hot carbon)and crystallizes them so they can pass out the exhaust. At the same time you can check to be sure your PCV valve is OK by making sure it 'rattles' when shaking it.
  8. tux

    tux LawnSite Member
    Messages: 36

    two questions on the water and AT fluid?
    how much water do you put down the carb(2oz or 0ne gallon} and is the motor at operating temp?
    on the AT fluid is two cap fulls the cap of a quart of fluid,and
    is the motor at operating temp? i have heard about the water in the carb but that was years ago,thanks for refreshing my memory i had for got about it
  9. 85w/350

    85w/350 LawnSite Member
    Messages: 244

    I always used the cap of whatever fluid I was using.....also...when was the last time you pulled the spark plugs? You may have fouled them up pretty good if you had reved it alot and the exhaust looked pretty potent
  10. linky

    linky LawnSite Member
    Messages: 151

    Speaking as a former auto tech. I would say that your engine is getting too much fuel.In all vehicles that i have diagnosed [rough running/black smoke from the tailpipe and cutting off at idle] the problem was a rich air to fuel ratio. I would make sure that the needle and seat are properly working and that the primary/choke plate is fully opened when the engine has reached operating temp.Carbon is the product of an incorrect fuel mixture[eccesive] As for cleaning carbon deposites i recomend trans. fluid or sea foam from the parts dealer.I have heard that water will work for removing carbon buildup but engines run and operate with patroleum products so i stick with them.ATF WORKS GREAT! To remove carbon buildup have someone hold the accelerator down 1/4 or 2500 rpm's drizzle the fluid into the carbs primary,if the engine starts to chug stop pouring until it clears up.It usualy takes about 6oz. to do a good job.It will smoke alot and i recommend a drive to get it good and clear.Ihope this was of some help good luck!

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