DON"T be an idiot!! ( A cautionary tale)

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david newbie

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:dumb2: So ive been struggling with my 372xp OE for a while now. Had it pressure tested, fine. Tried 4 different carbs, farmer tea, zama, original hd12 and another hd12 shipped in the mail from a member who was kind enough to loan me one. No matter what, it would start ok, although took too many pulls, idle ok ,ect. However, as soon as I put it in wood it would die immediately. I mailed it off to a member who took pity on me, and he found a clogged up fuel filter!!! It didn't look terrible, but it was hard to blow air through it. That seems to have solved it. Hopefully my silly story will help some future chainsaw dummyIMG_2426.jpeg
 
david newbie said:
:dumb2: So ive been struggling with my 372xp OE for a while now. Had it pressure tested, fine. Tried 4 different carbs, farmer tea, zama, original hd12 and another hd12 shipped in the mail from a member who was kind enough to loan me one. No matter what, it would start ok, although took too many pulls, idle ok ,ect. However, as soon as I put it in wood it would die immediately. I mailed it off to a member who took pity on me, and he found a clogged up fuel filter!!! It didn't look terrible, but it was hard to blow air through it. That seems to have solved it. Hopefully my silly story will help some future chainsaw dummyView attachment 1129851
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I have one that is embarassing me . A hoosky 240 that will simply not cooperate with everything I've tried.. Starts, sounds good then dies.. Changed the carb, plug, fuel lines, filter, ignition and wire.. Only thing I have not done is throw it outside and go get an Echo.. If I could put my finger on the " that's it", I would love to share my triumph.. However, I'm sharing my confusion and claiming stupid..
 
We all make mistakes and overlook stuff. I had a good running Stihl 066 here than I was looking to sell. I had a guy coming to look at it and I had pulled to top cover to clean it up a bit. For reasons I still cannot explain I mistakenly put a 25mm long bolt in the top cover on the flywheel side. It went right down between the fins. When I went to start it for the guy it appeared locked up. I was as red in the face as could be. He did not make it to the hard road before I realized my error and had it running.
 
If it's dumb, I've probably done it, that's how we learn. Understandable missing it, because despite it being one of the first things you're supposed to check, never been the problem with any of my saws and I always tend to skip past it and look deeper. If it's a fuel problem, usually my carb needs rebuilding/replacing. If spark, wire shorting somewhere or bad coil. One of the other common ones I never looked for until it happened to me was buildup on spark arrestor blocking exhaust, killing power of saw. Once I found that on one of my saws, I told an arborist friend at a botanic garden in NY where they were having power issues with their 880 and sure enough, that was the problem with it.
.358 win said:
I have one that is embarassing me . A hoosky 240 that will simply not cooperate with everything I've tried.. Starts, sounds good then dies.. Changed the carb, plug, fuel lines, filter, ignition and wire.. Only thing I have not done is throw it outside and go get an Echo.. If I could put my finger on the " that's it", I would love to share my triumph.. However, I'm sharing my confusion and claiming stupid..
Click to expand...
Checked the spark arrestor screen? Aside from that, lately I've been having some saws right on the edge of having enough compression to run or not, in need of new rings, or new rings and piston. Until I got a compression tester that did small engine readings properly, my compression tests were useless at telling me if I had low compression or not (they always read 50 psi too low). Done an accurate compression test on it?
 
Coralillo Lo Pro said:
If it's dumb, I've probably done it, that's how we learn. Understandable missing it, because despite it being one of the first things you're supposed to check, never been the problem with any of my saws and I always tend to skip past it and look deeper. If it's a fuel problem, usually my carb needs rebuilding/replacing. If spark, wire shorting somewhere or bad coil. One of the other common ones I never looked for until it happened to me was buildup on spark arrestor blocking exhaust, killing power of saw. Once I found that on one of my saws, I told an arborist friend at a botanic garden in NY where they were having power issues with their 880 and sure enough, that was the problem with it.

Checked the spark arrestor screen? Aside from that, lately I've been having some saws right on the edge of having enough compression to run or not, in need of new rings, or new rings and piston. Until I got a compression tester that did small engine readings properly, my compression tests were useless at telling me if I had low compression or not (they always read 50 psi too low). Done an accurate compression test on it?
Click to expand...
Arrestor screen is clean. Inside the cylinder looks normal.. Surely do need a comp test. Maybe I need to turn it upside down, my first thoughts were that it surely isn't old enough or have enough hours to behave this way. The part that goofs me off is the way it starts, runs 3 seconds then quits. I kept saying "electrical". New coil didn't change anything. I'm having much trouble keeping my temper in cheque..
 
I just got a GOOD lesson in BAD fuel. My brothers Echo CS-7310 took a dump. Hard to start, would BARELY run, then revved up and died out. Hum, sounds like a carb kit should fix that one. I took the carb off and it didn't look bad at all, vacuum tested the fuel line, but bought a new fuel line(s) anyhow and a carb kit. I also spark checked the coil and it seemed fine.

Got it all done and same thing....hum? Even though I ultra sonic cleaned the carb and very gently blew some air thru it I didn't remove the mixture screws.

So I backed them off 2 full turns each and fired it back up. For about 20 seconds it was doing the same thing, acting really lean and almost stalled out, then it went "pig" rich everywhere. I moved the mixture screws back to the original settings and good to go. Ran flawlessly for two tanks of fuel so I gave it back to him.

Well SOB yesterday he drags the CS-620PW over here doing the exact SAME thing (it was using fuel from the same fuel can). Instead of tearing it down I dumped the fuel, put fresh fuel in it and backed the mixture screws off two full turns. It started and acted lean EXACTLY like the CS-7310 but then after a few seconds went "pig" rich. I put the mixture screws back to the original settngs and flawless for the rest of the tank of fuel.

It appears that he got some bad fuel that clogged up the passages under the L and H" screws. Very odd that all it took was to back them off and let the new fuel clear things out, but that is all both saws needed to fix them..........
 
The one thing I have learned in 40 years is to not skip steps in diagnosis. Always dump the fuel and check the filters (replace the fuel filter). If you have vacuum and pressure testers check fuel hose and fuel vent. The list goes on. Visual inspection is VERY important.
Stihl places a lot of importance on the diagnosis sheet, to the point it is memorized. It gives you a checkoff in your mind so you check everything.
Now, will something get you once in a while? Oh yeah. Aftermarket parts are #1. Is the fuel actually coming out of the fuel hose when shook? Quickest way to check.
The best of us will still have to scratch our head occasionally, but the right mental tools let us keep our hair.
And a WHOLE LOT of common sense plays a big part.
 
.358 win said:
The dial indicator on my "thumb gauge" reads good compression. Hard to read the gauge when I stick it my eye.
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Aside from weird things with aftermarket carbs, like my brother's 42cc Craftsman or Poulan that wouldn't keep running after he replaced the carb til I ended up turning the high speed jet out 2 and a half turns to find the sweet spot, lack of crankcase pressurization from bad crank seals is often another cause of mystery behavior. Actually come to think of it, his problem may have been bad seals making it run too lean and I only balanced that out by running the carb much richer than normal. It still never ran great, but it ran.
 
I guessed about that fuel thing.. All my other saws are using the same fuel... They are a collection of red saws.. Orange ones are the problem ones.. One of the orange ones runs great. It's a 460, doggone thing runs like a scared whore. I did try and turn the mixture screws quite a bit.. ( the 240). That did affect the run time but it still quit.. That should tell me something of the aftermarket carb that was installed. Never had trouble such as this with anything before, definitely not my Jreds.. Still guessing and less than happy taking it apart again and again.
 
.358 win said:
I guessed about that fuel thing.. All my other saws are using the same fuel... They are a collection of red saws.. Orange ones are the problem ones.. One of the orange ones runs great. It's a 460, doggone thing runs like a scared whore. I did try and turn the mixture screws quite a bit.. ( the 240). That did affect the run time but it still quit.. That should tell me something of the aftermarket carb that was installed. Never had trouble such as this with anything before, definitely not my Jreds.. Still guessing and less than happy taking it apart again and again.
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Made a special trip quite a few miles away to get non-ethanol 90 octane. Next is a grenade
 
How many pulls did it take to collapse the fuel line? This was after they put bar oil into the fuel tank?
ROFL, the thing was flat...

We forget to check the simple stuff first.... I am glad that I switched out the chicom carb on my saw, but that is when I discovered that the fuel line had a split in it... simple stuff.
 
.358 win said:
I guessed about that fuel thing.. All my other saws are using the same fuel... They are a collection of red saws.. Orange ones are the problem ones.. One of the orange ones runs great. It's a 460, doggone thing runs like a scared whore. I did try and turn the mixture screws quite a bit.. ( the 240). That did affect the run time but it still quit.. That should tell me something of the aftermarket carb that was installed. Never had trouble such as this with anything before, definitely not my Jreds.. Still guessing and less than happy taking it apart again and again.
Click to expand...
Welcome to the nightmare I went through with my 045 and 056 rebuilds. Game of whack a mole. New everything and still wouldn't work, because just as I'd fix one problem, another would be created. Ignition wires would rub raw and short or break, did a bad bearing install on one saw I had to split the saw and do over, new piston rings got stuck on one after running a short time. Kept chasing carb problems when I'd rebuilt four carbs to try between the saws, cause carb adjustment would change things some, but in the end it was never anything to do with the carbs. It was always compression or ignition issues. Also, cheap aftermarket ignitions can apparently be a total crapshoot as to whether they work or not judging by reviews. The $15 one I got for my MS361 I just fixed worked out fine thankfully, but only after I put new piston and rings in. Had about 90-100 psi compression and wasn't til I took it apart I saw top of cylinder was melted off on one side and rings frozen on.
 

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