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Husky 141 not sucking up gas to the carb ...

Discussion in 'Chainsaw' started by woodbutcher80, Jun 9, 2013.

  1. woodbutcher80

    woodbutcher80 ArboristSite Member

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    hey guys .
    let me first say im not a beginner here , and have checked the basics. i love collecting husky saws and use all of them regularly as i need 6+ cords a year for my stove in the winter .

    that being said , im stumped .

    late 90s 141 . . . took it out from storage and it ran fine, slow revving little saw. it stopped running so i decided to clean the carb. now it wouldnt idle at all. took apart the carb, soaked it in chem dip for a day or so and still nothing . it would start but would die within 3-5 seconds . i think i put the high jet needle in the low jet needle hole .... i noticed the low jet needle has a finer tip that the high and thought maybe i messed up the hole in the ZAMA carb ?

    anyways , got a brand new walbro wt239 carb for 25$ just to have the zama around as a spare and the price was good . hooked it up , replaced the little green IMPULSE PIPE and black induction pipe (boot), and carb gasket and the carb wouldnt pull up fuel . i know what your thinking... check tank vent duckbill under the bronze cap ... i blew it out and its fine ... besides this was with a fuel hose going into a cup of gas!

    i did this to eliminate the tank being the problem . anyways , i tested the new walbro carb by hooking my mighty vac gauge up to the tiny hole on the top front face of the carb that the impulse pipe pulls from and tried to create a vacuum on the carb to pull gas out of the gas cup ... it goes up the hose about 2" , then nothing. it will hold suction pressure fine . i dont have a pressure gauge so i cant blow out to test pop off pressure(new carb though so its fine).

    test compression on cylinder ... 130 psi solid . bit low but not bad for a husky i think.

    i dont think i understand fully how gas is pulled up to the carb. this is a brand new carb and when i tried to get it to pull gas it wouldnt work... im thinking the cylinder vacuum pressure through the actual carb throat might help pull the fuel up too . remember now this has an impulse pipe , not a impulse hose hooked to the brass tube on the carb like the rest of my saws.

    any help would be great . when i put a little gas in the carb intake it starts up for a second.. same if i put in in the cylinder.

    im just stumped. probably something stupid. sorry this is so long ... just wanted to be thorough.
     
    Last edited: Jun 9, 2013
  2. woodbutcher80

    woodbutcher80 ArboristSite Member

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    heres a pic of the induction pipe and impulse pipe .. they are on the far left . the induction is the big oval carb boot , and the little sling shot rubber band tube is the impulse line notoious for cracking and causing a lean in the cut problem .
     
  3. woodbutcher80

    woodbutcher80 ArboristSite Member

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    well im stumped too ... back to tearing it apart. . .
     
  4. jmatteau

    jmatteau ArboristSite Member

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    Did you replace the impulse line and Fuel line? Does this model have a primer bulb?
     
  5. turbo885

    turbo885 ArboristSite Operative

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    I would pull the carb apart and make sure diaphrams are in the right order new carb or not they may not be right or have a pin hole
    BILL
     
  6. wcorey

    wcorey ArboristSite Guru

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    Not sure why the carb isn't pumping fuel on the saw but if I understand your external test, I do know why that doesn't work.

    The impulse line/hole is called that for a reason, it operates with the back and forth pulse from the crankcase pressure/vacuum.
    This positive/negative pressure/pulse oscillates a part of a gasket that is sandwiched across a small chamber and acts as a diaphagm.

    There are two little flaps integrated into the same gasket that are arranged over holes to act as one way valves,
    fuel going through one into the pulse/diaphragm chamber and can't go back so is pushed through the opposite one
    that then leads to the metering needle valve.

    So by only applying vacuum (or pressure) to the impulse passage, nothing should happen.

    The flaps can get stuck down on the carb body or get distorted with age and not seal, though with a new carb that shouldn't be an issue.
    Assuming there's two gaskets sandwiched together, one acts as a spacer, make sure they're stacked in the right order.
    The flaps need to be sitting flat on the holes and will be held away and not seal if the gasket order is wrong.

    Hope this is comprehensible the way I'm explaining it...
     
  7. machinisttx

    machinisttx Addicted to ArboristSite

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    :agree2:
     
  8. woodbutcher80

    woodbutcher80 ArboristSite Member

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    yes fuel line and impulse were replaced.

    wcorey . . .
    thanks for the explanation . i should have known that as the impulse line in some snowmobiles acts the same. i will check the order of the gaskets again but i highly doubt its the issue as i have 2 carbs... but i will check . has to be something simple as to why it wont suck up gas
     
  9. huskydude

    huskydude ArboristSite Guru

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    What about removing the fuel filter to see if it is clogged?
     
  10. half_full

    half_full ArboristSite Guru

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    I always put some 2 stroke oil on the impulse grommet when I put it on. I had one not seat correctly and it was difficult to diagnose. Double check that the impulse fit correctly.
     
  11. woodbutcher80

    woodbutcher80 ArboristSite Member

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    its not the filter. i had a cup of gas with no filter on it at all sitting next to the saw and it didnt suck it up .
    ill check that impulse again . i just used some spit to lube it up ... but ill try .
     
  12. turbo885

    turbo885 ArboristSite Operative

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    i had an impulse that wouldnt seal also i ended up puting a piece of rubber (NOT TYGON) fuel line in it instead of the impulse nipple and it sealed up fine
     
  13. woodbutcher80

    woodbutcher80 ArboristSite Member

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    well i pulled off the carb again , reseated the impulse tube(had a backup brand new one) and still nothing . i confirmed the gas line is fine and the tank vent too. i pulled the exhaust to look for scoring on the p/c , looks great with 130psi.

    only thing else to do is examine the plastic needle piece that the impulse tube connects to , maybe theres a crack in it .
     
  14. turbo885

    turbo885 ArboristSite Operative

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    i think you should pressure test and check around the impulse and intake boots i have had trouble with them both before
    bill
     
  15. woodbutcher80

    woodbutcher80 ArboristSite Member

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    only pressure test i can do is with the cylinder and my compression gauge. ... my mighty vac only has suction. . . need to buy one that puts pressure out . suggestions?
     
  16. turbo885

    turbo885 ArboristSite Operative

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    did you pull vacume on it if so did it hold
     
  17. woodbutcher80

    woodbutcher80 ArboristSite Member

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    held fine . checked it for a few minutes only though . ill try that again soon for longer period i guess.
    the piston and cyl were in great shape though. it has to be something with that impulse line since i switched that out since i saw a tear and now its having the gas sucking up problems. . .

    p/c for this arent expensive on ebay... but i only spent 40$ on this saw used about 3 yrs ago, and already spent 30$ for carb, $20 for misc carb kit(for old zama rebuild kit) and impulse etc. ...
     
  18. turbo885

    turbo885 ArboristSite Operative

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    i wouldnt put much money in that saw they dont bring anything when you sell. i bet that impulse is not sealed try a piece of hose instead of the boot. It is hard to tell without pressure. even a tire pump hooked in the spark plug hole and soapy water around the boots use your compression gauge hose but take the schrader valve out
     
  19. AKDriveSprocket

    AKDriveSprocket ArboristSite Guru

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    Put a little mixed gas in the carb or spark plug hole and start it. This will help getting the diaphragm to move faster. Some times I pull the air filter off and put my thumb on the in take of the carb. Meter valve?
     
  20. woodbutcher80

    woodbutcher80 ArboristSite Member

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    thanks guys , ill give it shot again .
    yes, i did throw a teaspoon gas in the carb inlet and it fires right up and bumbles for about 2-3 seconds and then quits obviously . wont take any throttle . i did this a couple times, thinking the same thing, priming the hose full of gas and carb ... nothing .

    metering valve? do you mean the float valve needle thing? i would eliminate all carburetor issues as both carbs are now in great shape.. just checked the gaskets and the order theyre in today too . .. ill have to focus my attention on the impulse part and pressure test as well.

    i can just hook up the compression tester, pull the rope starter 3-4 times until it gets to 130psi and then spray around with soapy water?

    thanks again .
     

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