What to check next ms460

brendonv

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Oxford, Connecticut
My original (5 year old full time saw) MS460 just up and decided to not run one day about over a month ago. I ended up finding a deal on a new/used 460 and 660 right after that so I really didn't spend much time on it.

Tried firing it up today when I was doing some saw maintenance. It's got a brand new carb and fuel line. Starts, revs a couple times, then bogs out like out of gas. Not really sure what to check next. :?

I'd like it to live the rest of it's life next to the firewood pile. Ideas/suggestions appreciated!
 
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  • #5
It ran great. It sat for a few weeks because I had to fix a rubber mount, then fixed that and tried to run it and no go.
 
Three basic components required for a motor to run-
Fuel (air and gas in the correct ratio and volume)
Spark (Strong enough to fire the fuel and delivered at the correct time)
Compression

Every single issue will boil down to one of these three systems. If you confirm one of these systems is good then you don't need to keep repairing or replacing parts in that system. If it sparks and runs then you know the spark is good. Sounds like a fuel issue. I know you have a new carb on it, but try swapping carbs with your other 460.
 
If I have a saw that wont start and has been sitting a long time I replace the gas in the tank and then pour gas on the air filter. Full throttle, no choke and they fire up nearly every time in a few pulls. There is enough gas on the filter to keep the saw running long enough to prime the carb which takes over by the time the filter dries out
 
Fresh gas in filter is a really good way to prime. Most saws it is easy to get to as well. Syringe is a good thing to squirt with so it isn't flooded.
In plug hole and carb throat will work as well, but easier to flood them.
 
It ran great. It sat for a few weeks because I had to fix a rubber mount, then fixed that and tried to run it and no go.

10 4 on checking the impulse line. When an AV mount is torn it can allow a good amount of slop in the system and this can sometimes cause the impulse line to pop off. Especially if it is an older line and is lacking flexibility. When the impulse is off it will start, rev high and then bog and die.
 
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  • #13
I have a new fuel line on it, is impulse line different than a fuel line? Not sure on saw terms.

I hope to tinker with it this weekend.
 
Impulse is different. Impulse allows vacuum pressure to move the diaphragm, part of the saw's fuel pumping system. Saws don't only run when level now. A line or directly through a hole in the carb manifold block.
 
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  • #16
Hmm. Can't say I remember seeing it, and def. didn't replace it. Will check tomorrow, thanks!

What happened with the AV mount was the screw snapped somehow. I gotta admit I ran it like that a few times. Then I got the screw out and since they are plastic threads it wouldn't hold a new screw, so I used a stainless bolt and got nylock nut to fit on the other end.
 
Here ya go .It's a little line that runs from the crankcase to the carb
 

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Another good practice is checking to see what wire might have got broke or pinched... If you are taking covers off to replace mounts, it can happen.
Sometimes over looked.
 
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