The muffler screen may be plugged.
041 Farm Boss trouble
- Thread starter Randy Andrews
- Start date
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thompsoncustom
ArboristSite Operative
no compression? maybe get a gauge on it or at least get some pictures of the piston shirt on the exhaust side.
Randy Andrews
ArboristSite Lurker
I’ll check this today!
Pulse hose, intake gaskets, inlet screen,fuel hose. Pressure test the fuel line. Known failure where the elbow is at the tank.
Spark test with a plug or a tester? At least open the gap on the plug to a 1/4 inch or more.
Does air filter base move if you try to wiggle it?
Switch and wire.
Can pretty much do one in my sleep anymore. Like doing Quadrajets in the 80s.
Does the compression hold the weight of the saw when held by the starter handle? That is a compression test.
Spark test with a plug or a tester? At least open the gap on the plug to a 1/4 inch or more.
Does air filter base move if you try to wiggle it?
Switch and wire.
Can pretty much do one in my sleep anymore. Like doing Quadrajets in the 80s.
Does the compression hold the weight of the saw when held by the starter handle? That is a compression test.
Randy Andrews
ArboristSite Lurker
Yes it will hold the weight of the saw. I’ll regap the plug and check the exhaust today if I can.
Fuel line, fuel filter and pulse hose are good.
Patrick1903
ArboristSite Operative
Not necessarily related to your specific issue, but at some point you would want to check the saw for air leaks. There are a lot of places this saw will leak. Good info on checking those possible trouble areas here.
https://www.arboristsite.com/threads/041-problem-and-theory.261143/
https://www.arboristsite.com/threads/041-problem-and-theory.261143/
Randy Andrews
ArboristSite Lurker
Thank you very much! After I check the exhaust screen, I’ll run down this checklist!
vtfireman85
ArboristSite Operative
I had a Honda Generator do this to me on one of our fire trucks, i did some serious head scratching, turns out the shaft broke on the throttle plate, it did it in such a manner that it didn’t fall out and would suck shut and stick, but it didn’t appear broken until I dismantled the carburetor. I know you said you cleaned it, but if you didn’t really dismantle, might be worth a look.
Randy Andrews
ArboristSite Lurker
Yeah, I completely disassembled it, and cleaned it as well. It all looks good as far as I can see
Patrick1903
ArboristSite Operative
I don’t think you said you pulled the muffler. Did you visually inspect piston/cylinder? Not too much sense getting into the weeds on troubleshooting if that’s not checked.
Randy Andrews
ArboristSite Lurker
That’s a good idea, I’ll pull the muffler next
vtfireman85
ArboristSite Operative
My FIL has a farm boss, IIRC it has points, not electronic? Seems like i had to clean them once, but my memory is foggy. Does the saw have hot blue spark going straight from the electrode or is it yellow and jumping around? A spark tester like this is cheap and effective at testing strength of a coil. Weak coil wont work well under compression also make sure your on off switch isn’t misbehaving, might be worth unhooking it just as a test, if it is carboned up or making intermittently it will mimic a bad coil but could potentially still produce spark.
We bought my FIL a 550xp to replace the farm boss, but he took the Stihl to his summer place where he continues to fight with it. I suggested stepping to the end of the dock and throwing it as far as he can out into the water last time he called scratching his head about getting it to run.
We bought my FIL a 550xp to replace the farm boss, but he took the Stihl to his summer place where he continues to fight with it. I suggested stepping to the end of the dock and throwing it as far as he can out into the water last time he called scratching his head about getting it to run.
Randy Andrews
ArboristSite Lurker
Spark looks steady and good. Switch stops the spark. I’ll dive into it more if the exhaust screen doesn’t fix the problem
Randy Andrews
ArboristSite Lurker
Hey man, it no longer holds the weight of the saw!
Thank you for the suggestion, I ordered a new piston and cylinder today.
Patrick1903
ArboristSite Operative
Post a picture of the piston and cylinder from the exhaust side. Or if you are already pulling the jug throw us a bone and snap some pics.
Randy Andrews
ArboristSite Lurker
Patrick1903
ArboristSite Operative
That’ll do it. The question is, why’d it happen? I have an 041 top end thread on here with very similar scoring as the basis for my new top end. In reality I should have salvaged the stihl cylinder and just replaced the piston. I was looking at cylinder just the other day as I was organizing some parts and it’s in pretty good shape.
I got the saw with the blown top, from my father in law. It had been sitting under his bench for 5 plus years and I took it. I wasn’t sure how much was done to it to investigate, but there were several missing screws, exhaust was loose. Seemed like a lot of vibration over 40 plus years had taken a toll. Wasn’t sure if something had gotten into exhaust or intake, carbon scoring, etc. no idea if the cause. It apparently just stopped running, I think with a puff of smoke.
SteveSr
Addicted to ArboristSite
That looks like something internal came apart like a bearing separator...
Randy Andrews
ArboristSite Lurker
Patrick1903
ArboristSite Operative
Is that the wrist pin and retaining clips you pulled out? Does the fact that they are not c shaped but have the ears on them indicate that they had been replaced previously?
