Chainsaw runs fine but stalls in cut after a few seconds

[MelonBoi1]

My chainsaw runs fine and cuts fine but when cutting, after a few seconds it will bog down a lot and then stall, in order to start it again I have to use the choke which basically just narrows it don to a fuel issue I think, the saw is a late 70s Dayton 2Z463 or Poulan 245SA but the thing is it never did this before it used to cut fine and it has a carb kit in it and fuel lines, I redid everything. Today I cleaned out the tank, replaced the fuel filter, cleaned the screen in the carb and it still does the same thing. I will go through the carb again tomorrow probably but for now I need answers.

[Guydreads]

I personally would check the metering lever. Make sure it's in the correct position. Make sure impulse isn't blocked. (I once had debris in the impulse tube that caused it to only start and run on choke). I doubt it has a spark arrestor screen but check that for debris. Check air filter for debris as they will bog a lot when dirty. Last thing you wanna do is start messing with the jets till EVERYTHING else has been eliminated.

[John Mc]

When it dies, if you loosen the fuel cap and then tighten it again, will it start and run normally? If so, you might have a plugged vent.

[MelonBoi1]

When it dies, if you loosen the fuel cap and then tighten it again, will it start and run normally? If so, you might have a plugged vent.

I definitely thought of that also, cap works as it should with new duck bill and it won't make a difference if I loosen it and tighten it again yet for some reason fuel is slowly driveling down the gas tank from the cap yet it vents fine, it never did this before

[MelonBoi1]

I personally would check the metering lever. Make sure it's in the correct position. Make sure impulse isn't blocked. (I once had debris in the impulse tube that caused it to only start and run on choke). I doubt it has a spark arrestor screen but check that for debris. Check air filter for debris as they will bog a lot when dirty. Last thing you wanna do is start messing with the jets till EVERYTHING else has been eliminated.

I rebuilt the carb already and did everything properly. Metering lever is set, there is no impulse hose on this engine. Spark arrestor screen is fine air filter is very clean I did everything already.

[Guydreads]

Have you checked for crankcase pressure and vacuum? Could it be a clutch issue where the clutch is binding under load?

[doc henderson]

what do you mean gas is driveling down the tank.  was it overfilled, or is there pressure building in the tank?

[MelonBoi1]

what do you mean gas is driveling down the tank.  was it overfilled, or is there pressure building in the tank?

Gas was slowly oozing put of the side of the cap

[MelonBoi1]

Also I noticed a vital clue, a big air bubble in the fuel line. Not the one in the tank but the one that goes to the carb. That probably means it is something with the tank venting and not the carb.

[Big_eddy]

In my experience, if a saw will idle fine and start to cut but then dies  after a few seconds in the cut, you have a serious restriction in the fuel supply. At idle, the pump section of the carb is able to keep up with demand, but when you add load and need more fuel, once the small amount in the carb is consumed, it starves. 
I've had it happen more than once on my 562s, and every time it was  because the fine screen in the carb was gunked up. Clean it and the problem goes away. But your carb may not have one.

I'd start with the fuel filter, then the fuel line looking for cracks or pinches, then the pump side of the carb including checking the metering lever a second time. And make sure none of the small passages in the carb are blocked.

If you see a bubble in the fuel line from the tank to the carb, then air is getting in somehow. There shouldn't be any bubbles in that line! Check it carefully for a crack or a leak at a nipple. Or perhaps the fuel filter is not sitting in the bottom of the tank for some reason.

[MelonBoi1]

In my experience, if a saw will idle fine and start to cut but then dies  after a few seconds in the cut, you have a serious restriction in the fuel supply. At idle, the pump section of the carb is able to keep up with demand, but when you add load and need more fuel, once the small amount in the carb is consumed, it starves.
I've had it happen more than once on my 562s, and every time it was  because the fine screen in the carb was gunked up. Clean it and the problem goes away. But your carb may not have one.

I'd start with the fuel filter, then the fuel line looking for cracks or pinches, then the pump side of the carb including checking the metering lever a second time. And make sure none of the small passages in the carb are blocked.

If you see a bubble in the fuel line from the tank to the carb, then air is getting in somehow. There shouldn't be any bubbles in that line! Check it carefully for a crack or a leak at a nipple. Or perhaps the fuel filter is not sitting in the bottom of the tank for some reason.

The metering lever is good, I can take the carb off to check again though, I just replaced the fuel filter but that didn't help. The fuel lines are brand new as stated before. If I pressure test the tank then the fuel cap will just release the pressure. Like I said this hasn't happened before and the screen inside the carb is clean.

[MelonBoi1]

I completely overhauled the fuel system and it does the same thing, however this could be because it doesn't have enough fuel, I am out of 32:1 and before some guy starts babbling on about how 50:1 is fine in this old stuff I don't care. This saw is in too good of a condition to just run 50:1 in it like I don't care, I don't use this saw to heat my home. I am a chainsaw collector.

[beenthere]

Mystery solved, it will not run without enough fuel. 

[doc henderson]

OK

[Big_eddy]

In my experience, if a saw will idle fine and start to cut but then dies  after a few seconds in the cut, you have a serious restriction in the fuel supply.

I completely overhauled the fuel system and it does the same thing, however this could be because it doesn't have enough fuel,

An empty tank does tend to restrict the supply of fuel. 

[doc henderson]

@MelonBoi1 maybe you can tell us more about you.  we are all trying to read between the lines and help.  you collect saws.  You are a jack of all trades.  what else should we know about you so we can try to help.  If you want to use a higher amount of oil in your fuel that is fine.  the comment about someone here babbling on about it implies you really do not want our opinion on it.  so why bring it up.  We are mostly thick skinned.  Most of the suggestions you seem to have already checked or done, or do not want to try.  We have all kinds of chainsaw experts on here, and some are wishing you well and good luck, which is code for they are done trying to help based on your responses.  I mentioned this early on in one of your posts.  Can you help us with your other work experience and how old you are?  we are looking for objective replies to our questions.

[Keepfixin]

It does sound like a fuel restriction or a fuel leaning problem. I would try like Guydreads said. Crankcase pressure and vacuum test. Sometimes that spring in the seal falls out of place and ends up on the crankshaft which causes a leaning out problem. Some older guy who worked on everything told me about this issue.

Also a bearing could be going out which under load could pull the crank towards the wood and stress the seal which could be another possibility of air leaning. Take the sprocket cover off and clutch then grab ahold of the crank and see if there is any play up and down or side to side. Kinda like checking your tie rods or ball joints on a car. Works also on the flywheel side also. Sometimes an indicator is when you start hearing a metallic noise or see wear marks on flywheel magnets from coil. Then you definitely know its a bearing!!