So I'm pretty lost and in need of help

[Shendron]

I have a ms 460 magnum and was cutting at my brothers property. I ran some pre mix stihl fuel through it and it ran great, but when I got home and went to use it it will run for like 5 seconds and then die. I can't keep the saw running. Any thoughts for me please. I'm kinda new sorry if it seems like a dumb question

[killamplanes]

Fuel pickup in the tank,  clogged carb jet? Man that could be the sympton of about anything.  Good luck I bet it's nothing major. But if you have to pull the fuel tank for fuel filter or somethin it's not fun.

[Hilltop366]

Is the tank full? If not fill it up and try again, also pull the spark plug, wet or dry?  That might give some clues.

[thecfarm]

Will it idle? Meaning for 30 seconds,than when you press the throttle it dies?
And welcome to the forum.

[scully]

I have had dry rotted fuel line sucking air . that will cause problems for sure .

[SawTroll]

It could be as simple as a clogged tank vent - but usually it would take more than just 5 seconds before it "died" then, more like a few minutes.

If it runs fine with the fuel cap open, it is the tank vent - so just try, if nothing else to rule it out.

As it sounds, I suspect the fuel lines, as others did.

[HiTech]

Could be the spark arrestor screen in the muffler

[joe_indi]

Screen in the carb could be clogged. Or the jet valve might be leaking. Or as simple as an impulse hose that has come off at the crankcase end

[timberjack 240a]

No such thing as a dumb question. Same saw, same problem, might not be same solution. Let my brother borrow my saw. Got it back so dull it would cut better with the chain on backwards and it wouldn't run. After beating my head against the wall forever trying to figure it out. I asked someone. I told him I had checked everything and cleaned everything. He said pulse line? There is a small fitting coming out of the back of the engine that should have a little rubber line on it. You should be able to see it if you look down between your air cleaner cover and engine cover. Turns out my brother got the saw pinched. Yanked on it so hard the line came off. Easy fix with a small pair of needle nose.