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CS3400 carburator repair breaks oiler

Discussion in 'Chainsaw' started by ralphbsz, Oct 22, 2007.

  1. ralphbsz

    ralphbsz ArboristSite Lurker

    Jul 19, 2003
    Likes Received:
    Northern California
    Short story: The chain oiler on my Echo CS3400 broke, when I rebuilt the carburator. Weird. Don't know how to fix it.

    Long story: I've had this CS3400 for about 9 years, and it gets maybe 10 or 25 hours of use per year (serious homeowner with firewood needs); this is my limbing/climbing saw, the big stuff is done with a Stihl. The saw was not barely starting and running badly, and I suspected the diaphragm in the Walbro carburator (the California gasoline, with all its MTBE and Ethanol, has been tough on those parts). I got the carb rebuild kit at the local store, and while we are at it, got some replacement fuel hose and new fuel filter (I've had a Stihl 26 fail due to cracked fuel hoses, and while I have the saw open might as well replace all the parts in the neighborhood).

    Rebuilding the carb went pretty well, I replaced all the parts that came in the rebuild kit, except for one of the small red caps over the needles: I could only get it out by destroying it, so now the idle needle is running without the cap. I hope that's OK. If anything thinks it is not OK, I can order the needly / limiter cap rebuild kit, but getting those caps in or out is really tough. Adjusting the carb using a tach afterwards went without a hitch (thank god Echo has clear instructions in the manual), and the saw starts and runs great now.

    The problem is the fuel hose. I pulled off all the old fuel hoses, there are several: obviously fuel filter through gasket into carb, then one from a barb at the tank to primer bulb, primer bulb to carb, and finally barb at tank going back into the housing. The stupid thing is: I tried to pull of that last hose, thinking that it connected to another barb; I didn't now that that hose is long, and vanishes into the chain housing. I managed to pull maybe an inch of it through before noticing my mistake. So I took the cover off, and I can't see for the life of me where that gasoline hose vanishes into: seen from the flywheel side it seems to dive down along the engine, and vanishes. Since I don't know how to get into the housing past the flywheel, I decided to leave things alone.

    So far, so bad. Since then, the chain oiler has been working intermittent. First time I ran the saw after that, the oiler was going WAY too fast, leaving a trail of oil everywhere. Oops. I refilled the oil tank. Now suddenly the oiler has completely stopped working. Seems that pulling on that gas hose has completely screwed up the chain oil pump.

    Questions: Can someone explain to me how the chain oil pump on the CS3400 works? And whether my theory that pulling on that gas hose broke the oiler is right? And where that gas hose goes to? And how I get in there to fix the problem? I'm loathe to pull off the flywheel, that might be beyond my skills; are there some tricks on how to hold the flywheel while undoing the nut on it (without breaking anything, BTDT)? And where to find a maintenance manual, or at least an exploded diagram of the CS3400 on the web?

    Apologies for the typical amateur mistake of trying to tackle maintenance that's a little too difficult for me. But other than the small screwup of the limiter cap on the carb, and the big screwup of pulling on a hose that isn't intended to be pulled off, the carb rebuild job went very well.

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