361 spool up problem?

[MuleyJ]

This saw is about 4 years old an I have owned it since new. It has been muffler modded and has run very well. The saw has compression in the mid 160's. The saw starts as it always has and runs fine until it is warmed up completely. At that point on throttle it hesitates a bit then catches itself and spools up as it should. At first I thought it just needed a slight L screw tweak. The problem exists when the L screw is set to highest idle through 3/4turn CCW from high idle. Apart from this the saw runs great and keeps a good tune on the high side all day long. I took the carb off last night and went through and everything looked as it should. Went ahead and took everything apart and cleaned thoroughly with carb cleaner and reassembled. Same problem today. I guess the next step is to put a kit in the carb. Anyone know of anything else to look into?

 

[blsnelling]

Did Lakeside list the 361 as one of the saws with an accelerator pump in the carb? You may need a new carb.

 

[MuleyJ]

Looks like it does.

Now you made me go look it up!


Accelerator pumps:

MS200/T
MS192/T
MS270/280
MS341/361
MS441


All current USA saws except the 210/230/250 use intelli-carbs.

Yes. The trend is towards leaner idling saws that will need an accelerator pump... great...


I forgot the above had accelerator pumps as apart from the ZAMA carb on the 200T, they NEVER give any problems.

So whats the deal with the accelerator pump?

 

[gandrimp]

Accelerator pumps give a small squirt of fuel when you throttle up. It helps with stumble that the leaner idle causes.

 

[Andyshine77]

Also check the H speed screw to make sure it's not lean, this can cause acceleration issues as well. I'm sure you already know this, but hay it's worth a try.

 

[MuleyJ]

I am convinced that this is not an adjustment issue. This saw has always been a little finicky to tune, but until recently has not had any issues. I took apart the carb again last night and found the accel pump in the throttle shaft housing. Unfortunately I have to remove a welch plug to remove and inspect it, so I am undecided on what to do. I did some searching and it seems that I am not alone. Some have just swapped out for new carbs and the problem is solved.

 

[albert]

The 361 I have now and one I had prior, both muffler modded, needed to be set leaner than most saws on the L. If set any richer they would pool fuel if let idle more than a few seconds when hot and stall if tilted. That probaly is the reason they have the accel pump. They also have an intake boot with a drain port if I remember correctly. You may very well have a pump problem.

 

[MuleyJ]

The 361 I have now and one I had prior, both muffler modded, needed to be set leaner than most saws on the L. If set any richer they would pool fuel if let idle more than a few seconds when hot and stall if tilted. That probaly is the reason they have the accel pump. They also have an intake boot with a drain port if I remember correctly. You may very well have a pump problem.

Mine has always wanted to be real lean on the low side too, and it is for sure the fussiest saw I have to tune. I'll see how long it wants to run well now. If it acts up again I will likely just buy a new carb.