Got another stubborn one.. Stihl 017

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Interesting, following along.
Do you have a spark tester which you can extend the gap the spark has to jump to see just how good the spark really is? I had a saw one time that had spark but wouldn't fire added fuel, so I took a good running saw and swapped in the known good plug, and it fired.
Also, I have a messed-up shoulder so holding a saw upside down while I crank the heck out of it is very hard for me, but I have done that. My latest adventure doing this I removed the muffler and the plug and let the saw "air out" for a couple days. Fired right up next time I tried it. Though this is likely not your issue it is just what I did to a severely flooded saw recently. Good luck with the saw. JeffinMaine
 
Compression tests only test the combustion chamber above the piston- not going to tell you if excessive air is being pulled into that mix through the crankcase proper and up through the transfers.
It would have to be a big leak for it not to fire at all if you put fuel in spark plug hole.
 
Interesting, following along.
Do you have a spark tester which you can extend the gap the spark has to jump to see just how good the spark really is? I had a saw one time that had spark but wouldn't fire added fuel, so I took a good running saw and swapped in the known good plug, and it fired.
Also, I have a messed-up shoulder so holding a saw upside down while I crank the heck out of it is very hard for me, but I have done that. My latest adventure doing this I removed the muffler and the plug and let the saw "air out" for a couple days. Fired right up next time I tried it. Though this is likely not your issue it is just what I did to a severely flooded saw recently. Good luck with the saw. JeffinMaine
I had a spark tester, knew exactly where it was, went there and it was gone. Another mystery of moving. I think maybe wife's getting rid of my tools, one at a time. In lieu of testing I have several spark plugs and probably can find a module around here someplace. I have a spare flywheel also.
 
I find it odd that so many do not feel the need to vacuum and pressure test on a saw with age. First place I go in the shop. At least 75% will have it.
It's been brought up. Maybe in warmer weather when I can spend more time in the garage I'll get a little more involved. Right now I'm just going out there to feed the cat and I tinker a bit while he's having his breakfast, then I go back in the house and take him with me. I don't usually spend more than a half hour on the saws.
 
Really?
A loose engine pan is a pretty good leak.
Yeah, I've done this for several years and have yet to see one that won't hit if you put about a half teaspoon of fuel mix into the combustion chamber. Unless of course something is wrong with compression or spark at the right time. In a day or two I'll change modules and see if that helps.
 
Really?
A loose engine pan is a pretty good leak.
Yeah, I've done this for several years and have yet to see one that won't hit if you put about a half teaspoon of fuel mix into the combustion chamber. Unless of course something is wrong with compression or spark at the right time. In a day or two I'll change modules and see if that helps.
doesn’t matter how bad the air leak is, with raw fuel in the combustion chamber, the mixture should go from too rich to too lean as you continue to pull it over and at sometime it SHOULD fire unless it’s already flooded or something else wrong with it.
 
I find it odd that so many do not feel the need to vacuum and pressure test on a saw with age. First place I go in the shop. At least 75% will have it.
Maybe. But, if he putting fuel straight in the spark plug hole and it will not light it is not because of an air leak.


I'm sort of leaning toward he keeps flooding it.
 
I have a Stihl 017 I've been working on for a friend, trying to get it going. I put fresh fuel in it, checked spark and it's okay, new spark plug anyway, compression tested at 130 so it should be okay. Squirted a small amount of fuel in spark plug hole, put it back together and it wouldn't hit a lick. Tried another spark plug and still wouldn't hit. I would think the thing should hit at least once with fuel in the chamber, spark, and compression. I'm not sure if I checked it for the muffler being clogged but I'll try that tomorrow. What do you think?
Look at the piston and rings for damage, you can have 130, and it could be all scored up.
 
doesn’t matter how bad the air leak is, with raw fuel in the combustion chamber, the mixture should go from too rich to too lean as you continue to pull it over and at sometime it SHOULD fire unless it’s already flooded or something else wrong with it.

Depends on the scenario- try to start the saw as per normal (with a large air leak), pull rope umpteen dozen times for no result- case full of raw fuel by this stage- add more raw fuel via the plug hole and still wont go.
Air leak was the initial point of blame- subsequent flooding compounded the issue.

Does not really matter- its all a guessing game by keyboard- but I tend to use pressure and vacuum tests as a first port of call on old unknown to me saws long before I reach for a compression tester.
OP's saw and issue- he is free to go about diagnosis as he sees fit.
 

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