Craftsman Chainsaw won’t accelerate

My chain saw (Craftsman 358.360260 16”) is giving me great grief. Ever since I got it (dad died, and I was the only son) I’ve had to coax it to get to accelerate from an idle. However, starting a few weeks ago, things started getting progressively worse.

It started with it shutting off if I let it idle for more that about 1/2 a minute, then it progressed to stopping if I allowed it to idle at all, then it got very hard to start, then I had to prime the heck out of it to get it to start then finally it would not run at all.

I bought and installed a new carburetor and it will now starts and idles but I cannot get it to accelerate from idle. (Each time it bogs down and dies.) The guy I talked to at Walbro said that if were to buy a new carburetor, I would not have to adjust it.

I thought that the in-tank fuel filter was okay because when I disconnected the fuel line from the carburetor an oz or so of fuel spurted out, but I replaced the filter anyway.

Sooo…

1. Any thoughts?
2. Someone suggested to someone with a similar acceleration problem that they should replace the fuel lines. The theory was that old lines may collapse when the engine starts sucking hard. However, I am reluctant to pull out the lines because of that fuel spurting thing (when I disconnect the fuel line from the carburetor). Where is the pressure coming from? If I start the saw, let it die while attempting to accelerate, remove the gas cap and replace it and then disconnect the line it will spurt out about 1 oz of fuel. However, if I then just remove the fuel cap and replace it and then remove the line from the carb it doesn't spurt at all. Therefore the pressure in the line does not seem to be from a pressurized fuel tank.
   
   The reason I am reluctant to pull the fuel line out is that I am afraid there is some type of diaphragm or bladder somewhere that somehow supplies the fuel to the carb under pressure. (This chain saw doesn’t seem to have a separate fuel tank that you can see through. Instead the fuel “compartment” is part of the saw’s outer casing.) I’m afraid, I won’t be able to thread the new line past or reconnect it to what ever is generating and maintaining the pressure.
3. Isn’t the fact that the fuel, in the line, is under pressure after it dies, a good indication that it the carburetor was getting enough fuel?
4. One other thing. Before I replaced the carb, I could get the thing to start only after pushing the primer/purge bulb several times. When the saw was hot I would hear some popping/cracking sounds (like someone dripped water on to a hot burner of a kitchen stove. It was kinda scary, like fuel was being pump on to something hot). This confuses me because I though the primer/purge button sucked fuel from the carb instead of pushing it into the carb.

Thank you in advance.

Wayne

 

The guy at walbro was wrong. Just because a carb is new doesn't mean it is properly tuned exactly for your particular engine. There should be 2 mixture screws side by side. The one farthest from the engine is the high speed screw. Try backing it out 1/8 turn or so.

Your thoughts about the fuel lines... I haven't seen that happen on these saws. The pressure is from the tank. The pressure in the lines also says the lines aren't cracked or leaking, so the lines and fuel supply should be fine. The crackling/popping sounds you heard may have been from the old carb leaking fuel into the cylinder when it was hot. Does this saw have good compression? If it was getting too hot, it might be cooked.

 

Thank you for your response and suggestion.

I finally grew a pair and turned the screws. It it now running perfectly (asside from producing a little smoke before it gets fully warmed up). I had to turn both adjustment 1/4 turn counter clockwise.

Thanks again,

Wayne