Kind of a side note, what flange did u use to pres/vac test? Is it a stihl part?
Need help with MS362 issue...
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What have you tried on the H and L screws? Limiter cap still on the H? I rebuilt a 362 last week (the one above with the broken piston) and the L screw was off just enough that it wouldn't start and advance throttle when I put a new piston and cylinder on it.
The two symptoms that will follow carbs and create dieing while idling and poor acceleration are the tank vent and the fuel line leaking. I have had fuel lines leaking around the inlet nipple on the carb that cause the problems you are having. The lines will look o.k. and even pass a pressure check from the carb end because the nipple on the pressure pump is bigger than the carb nipple. I always check fuel lines from the filter end while the other end is still installed on the carb.
Just tossing around ideas. I feel your pain...I've been there.
The two symptoms that will follow carbs and create dieing while idling and poor acceleration are the tank vent and the fuel line leaking. I have had fuel lines leaking around the inlet nipple on the carb that cause the problems you are having. The lines will look o.k. and even pass a pressure check from the carb end because the nipple on the pressure pump is bigger than the carb nipple. I always check fuel lines from the filter end while the other end is still installed on the carb.
Just tossing around ideas. I feel your pain...I've been there.
Yes, bring 'em all . . old, new, and even ones that won't fit!
Yes, Stihl part. I borrowed it from my dealer, but the service manual says its part number 1140 890 1200.
I've spent an inordinate amount of time messing with the screws. Doesn't mean that's not still the problem, but after the carb disassembly & cleaning I started them back at factory spec (limiter on H removed) and went from there. Good thought on testing the fuel line from the filter end - I'll try that.
What sucks is that now (or at least one go-round after p/v testing) the saw ran & cut great, but just wouldn't start after slowly dying out at idle after cutting (with spark still present). I'm going to try running it again tomorrow and see what happens.
Man what a PITA.
Did you vac check the fuel tank from the fuel line? Check the impulse line for leaks when you pressure and vacuum tested the engine? Check gaskets and intake manifold? Double check compression with a different tester as the compression was slightly low. Good OEM fuel filter? Fresh fuel mix? Were the carbs you installed known good ones?
Did you vac check the fuel tank from the fuel line? Check the impulse line for leaks when you pressure and vacuum tested the engine? Check gaskets and intake manifold? Double check compression with a different tester as the compression was slightly low. Good OEM fuel filter? Fresh fuel mix? Were the carbs you installed known good ones?
If using a Stihl plug for the two intake channels, it automatically also tests the impulse line, that also checks the intake boot. I test the fuel tank by pressurizing the tank through the fuel line from the carb end. It should hold pressure. With vacuum applied it should not hold vacuum.
I pressure tested the fuel tank, but vacuum testing it only results in no vacuum being generated due to a functioning tank vent. There is not a traditional impulse line on this saw - it's integrated with the intake boot. Any hole or compromise to a line, gasket, or manifold would have shown up during all of the pressure & vacuum testing.
That compression isn't where I would like it to be, but it's more than enough to have a good functioning saw.
The fuel filter is OEM and brand new. The fuel mix is a fresh as it gets and consists of non-ethanol gasoline with Stihl HP Ultra oil.
The carbs were off of saws at a dealer that were brought in for damage repair. I can't say with 100% certainty that they were all good carbs, but I'm willing to hedge my bets that I wouldn't happen to find three carbs all with exactly the same performance issue. As described, the saw behaved identically with every carb tried...
Try to get it running and lift the handle up and down to see if there is a change in rpm indicating a slight tear in the intake boot.
Well, unfortunately I'm just too damn stubborn to walk away from this saw despite my threat to just post it on eBay for parts.
I ordered a new OEM carburetor and set of rings. If either or both of these don't make this possessed saw run correctly I'm just going to keep it on the shelf as a reminder that I am not capable of fixing anything as I often tell folks I am.
The final result should be posted next week........
I ordered a new OEM carburetor and set of rings. If either or both of these don't make this possessed saw run correctly I'm just going to keep it on the shelf as a reminder that I am not capable of fixing anything as I often tell folks I am.
The final result should be posted next week........
Well crap.
Sorry to hear it is getting to you like that. You will figure it out it just takes time. And I will be looking forward to hearing from you on this interesting problem. Thanks for posting.
Slight modification to the plan. I'd suspected for the past week or two that my compression tester was starting to test inaccurately high. I was able to borrow ELECT6845's tester for this saw. My tester had it at just a hair under 150 psi. When I put Joe's on it the number was just a hair over 130 psi.
In light of that I pulled the top end and checked ring end gap. My feeler gage set only goes up to .035" and both rings had a gap slightly in excess of that. In talking to my dealer he said the symptoms the saw was displaying could plausibly be from low compression. So, I cancelled the new carburetor for now and just ordered a set of rings. I'm not going to get my hopes up, but that would be a much cheaper fix than a new carburetor.
I'm hoping the rings will be in this week yet...
In light of that I pulled the top end and checked ring end gap. My feeler gage set only goes up to .035" and both rings had a gap slightly in excess of that. In talking to my dealer he said the symptoms the saw was displaying could plausibly be from low compression. So, I cancelled the new carburetor for now and just ordered a set of rings. I'm not going to get my hopes up, but that would be a much cheaper fix than a new carburetor.
I'm hoping the rings will be in this week yet...
Low compression would do it for sure, but those are funny symptoms. If it still acts up after installing the new rings, the fuel line may be collapsed internally.
Truthfully, I ruled out a collapsing fuel line since it will bog & die immediately if I yank the throttle - just didn't seem like the line could collapse that quickly. Hell, I could get a bigger rev out of a saw with a small shot of fuel in the intake. It's a good thought though, and now that you've got me thinking about it I'm almost certain I have a new fuel line I bought for an MS391 repair when the line ended up coming with the new tank housing. These saws share that part, so if I can round it up I'll just swap that out while I have it heavily disassembled waiting for the rings. Thanks!
john_bud
ArboristSite Operative
Every time I think of something to check, the next post is you trying it and I not working.
Sorry no help, just sympathy!
Sorry no help, just sympathy!
Hey man, I appreciate you checking in regardless! I've had too many false hopes with this saw, but at least with this bit of cash & waiting time I can take comfort in knowing it was needed and not just some shot in the dark.
Next step is perusing eBay to find a nice Snap-On compression test kit. I learned my lesson buying a cheap one the first time around. It's had a lot of use, but no abuse, and it barely lasted a year...
john_bud
ArboristSite Operative
On the bright side, it's not some simple issue!
Good luck
Good luck
Did you check the intake boot?
As mentioned before, it passed pressure & vacuum tests, so that eliminates a compromised intake boot. Today when I had to remove the intake in order to pull the cylinder off I took a look at it and there are no visual clues of an issue.
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