Ms310 running issues. Totally confused!

[Fatherwheels]

That’s a good idea. Never even considered that before!

Coil issue maybe. I had a saw with a loose flywheel,
that is how it went, would not stay running unless
the throttle was held 1/4 open, would rev out, but
would not idle, and a torture to start.

 

[slowcar281]

Coil issue maybe. I had a saw with a loose flywheel,
that is how it went, would not stay running unless
the throttle was held 1/4 open, would rev out, but
would not idle, and a torture to start.

I don’t think this is my issue, but I’ll certainly check it again. I used my stihl plastic piston stop and tightened the flywheel nut with a 3/8 ratchet fairly tight. I don’t have any problems starting the saw, and it will idle although not very well

 

[Fatherwheels]

10-4, could only be an air leak then.

Yep, something cooked it the first time round.
Don't these saws have trans fare covers that fall off,
maybe they are loose as in no longer bonded to the cylinder.
Try using less pressure and less vacuum during the test
and watch if that falls, this test usually shows up leaks that
are sealed up with the high pressure when running, but as
soon as you try to idle the pressure drops and the seals that
held up under higher pressure can now leak for want of pressure,
this could mean a stiffish lip on a seal, or just a badly fitting / sealing lip.
Isn't there two types of seals for these saws, one that pushes in to a non
split case, and another that is to be used if the case is being assembled
compressing the outer seal against the case, these seals are not intercha
-ngeable.

 

[lone wolf]

That’s a good idea. Never even considered that before!

Works every time .

 

[lone wolf]

I don’t think this is my issue, but I’ll certainly check it again. I used my stihl plastic piston stop and tightened the flywheel nut with a 3/8 ratchet fairly tight. I don’t have any problems starting the saw, and it will idle although not very well

Dont you have a 3/8 impact gun?

 

[slowcar281]

Dont you have a 3/8 impact gun?

Lol yup at work.

 

[grizz55chev]

Well that certainly could be the issue but why with the new carb did it still act up? Dunk that saw in a bucket of water while pressure testing.

That's my last resort, when everything else has not worked! it's messy, but sure fire.

 

[a. palmer jr.]

I'm going through the same thing with a Homelite XL. In my case I have about a dozen used carburetors and not one of them are any good. I've checked everything on these saws and I'm pretty sure the carb is the culprit but don't have a good one to test it on the saw.

 

[slowcar281]

HOLY CRAP I THINK ITS FIXED! I stopped and picked up a new oem carb. I also bought one of the fuel filters that fits a ms660 and put that on too. It’s much bigger than the stock one and it’s orange ( if that means anything )

Saw idles well now, and returns to idle well too. I didn’t even remove the limiter caps, I just wanted to see how it ran with them in place. I have no idea how far the needles are out from the factory but they allow 3/4 turn inward from the full rich stop. With the H screw up against the stop it only ran about 11,200 rpms. I had to turn it in 1/2 turn to get about 12,700 rpms. I had to lean out the L screw about 1/16 of a turn. Adjusted the idle to 2500 rpms or so. Spec is 2800 and that seems & sounds too fast.

I cut a couple pieces of wood. I didn’t have anything big to cut, but the saw runs really well. Returns to idle quickly.

I honestly can’t believe a carb fixed it.

Thanks to everyone who offers input and opinions!

 

[grizz55chev]

HOLY CRAP I THINK ITS FIXED! I stopped and picked up a new oem carb. I also bought one of the fuel filters that fits a ms660 and put that on too. It’s much bigger than the stock one and it’s orange ( if that means anything )

Saw idles well now, and returns to idle well too. I didn’t even remove the limiter caps, I just wanted to see how it ran with them in place. I have no idea how far the needles are out from the factory but they allow 3/4 turn inward from the full rich stop. With the H screw up against the stop it only ran about 11,200 rpms. I had to turn it in 1/2 turn to get about 12,700 rpms. I had to lean out the L screw about 1/16 of a turn. Adjusted the idle to 2500 rpms or so. Spec is 2800 and that seems & sounds too fast.

I cut a couple pieces of wood. I didn’t have anything big to cut, but the saw runs really well. Returns to idle quickly.

I honestly can’t believe a carb fixed it.

Thanks to everyone who offers input and opinions!

So since you did 2 things, how do you know which one was the smoking gun? Just for curiosity, throw the old filter back on and do a test. Wouldn't be the first time the filter was the cause!

 

[slowcar281]

So since you did 2 things, how do you know which one was the smoking gun? Just for curiosity, throw the old filter back on and do a test. Wouldn't be the first time the filter was the cause!

I’m gonna say it was the carb but tomorrow I’ll try the old filter again. Unless it was defective, it was brand new too. It was the smaller one with the white filter element

 

[a. palmer jr.]

The only reason I don't try a new carb on the XL I'm working on is the new carb costs about twice as much as the saw would be worth..

 

[Aripper]

I was given a complete ms310 that was deemed trash. I tore the entire saw down, cleaned and rebuilt it.

I cleaned the stock cylinder and removed the transfer. Installed a meteor piston, caber rings, and new bearings. New oem impulse line, crank seals, fuel line and fuel filter. Pressure tested the saw and it holds 8 psi and vacuum just fine. Double and triple checked the intake boot for wear.

I bought an OE carb kit for the oem hd21c carb and installed that.

I cannot get this thing to idle properly. It’s up and down constantly. You can’t get the idle to calm down at all unless you richen the L screw so rich that it smokes at idle and full throttle acceleration is poor. Even with the H screw turned all the way in, it will only rev to 12,500 rpms. It just runs like crap overall, but starts just fine. I was shooting for stock specs of 13,000 rpms. The muffler is completely stock.

I talked to our small engine mechanic at work and he had a brand new walboro hd19 sitting on the shelf. He told me to take that and try it.

SAME EXACT PROBLEM. Runs no different.

Anyone have any ideas? I checked the coil gap and made sure the flywheel key wasn’t sheared.

I’m out of ideas other than buying a new oem carb and trying that. Dealer said they are 80 dollars, but I’m not convinced that will fix it.

Possible the intake and/or exhaust ports have been bored too much, you need a whole new head to fix that problem. Seen that before by my own doing, just got carried away in in my enjoyment of Stihl saws. Thats my experience with that exact failure.

 

[slowcar281]

The only reason I don't try a new carb on the XL I'm working on is the new carb costs about twice as much as the saw would be worth..

I did the same thing but worse on an 029 super I rebuilt into an 039. By the time I was done with it the cost far exceeded what that saw cost new. I want to say I had over 400 dollars into the rebuild plus I actually paid for the burnt up saw itself.

But it was a huge learning experience. That was the first time I had ever torn down a clam shell saw.

 

[stihltech]

A new carb is the fix. I replace half of them. Have to remember age and abuse before you got it. Part of almost every overhaul. Kit is almost a waste of time.

 

[Fatherwheels]

I don’t think this is my issue, but I’ll certainly check it again. I used my stihl plastic piston stop and tightened the flywheel nut with a 3/8 ratchet fairly tight. I don’t have any problems starting the saw, and it will idle although not very well

Just some advise, don't use the piston stop.
They do damage the piston, use some starter rope,
and use an impact gun to remove nuts or the clutch.
Tighten against the pull cord shoved in through the plug hole,
being careful the rope does not inter a port and or get sliced off
with the piston.
Don't tighten with the impact wrench, too dangerous, might strip threads.

 

[Fatherwheels]

HOLY CRAP I THINK ITS FIXED! I stopped and picked up a new oem carb. I also bought one of the fuel filters that fits a ms660 and put that on too. It’s much bigger than the stock one and it’s orange ( if that means anything )

Saw idles well now, and returns to idle well too. I didn’t even remove the limiter caps, I just wanted to see how it ran with them in place. I have no idea how far the needles are out from the factory but they allow 3/4 turn inward from the full rich stop. With the H screw up against the stop it only ran about 11,200 rpms. I had to turn it in 1/2 turn to get about 12,700 rpms. I had to lean out the L screw about 1/16 of a turn. Adjusted the idle to 2500 rpms or so. Spec is 2800 and that seems & sounds too fast.

I cut a couple pieces of wood. I didn’t have anything big to cut, but the saw runs really well. Returns to idle quickly.

I honestly can’t believe a carb fixed it.

Thanks to everyone who offers input and opinions!

Great news, I hope your saw serves you well.

 

[magreeable]

I bought an new MS310 years ago. I really like it.

 

[Lightning Performance]

The only reason I don't try a new carb on the XL I'm working on is the new carb costs about twice as much as the saw would be worth..

Remove all the bits and soak then in acetone. Being older and run on natural oils they will gum up in places you can not see. Removing the welch plugs is when you can see the nasties and clogged fuel feed ports. Sometimes it's just a simple tap with a hammer to set a loose seat area and your off to the races. Stiff diaphragm can give the same bs idol.

 

[James Sawyer]

So... I understand the saw leaked tested fine... that's good it weeds out a lot of stuff. I'd check the fuel filter and line to start with. Next I'd check the needle valve setup (height) and verify the diaphram are all in correctly, then pressure test the carb. If it has a compression release valve you might just plug it or replaced it but if it had a problem the leak test should have verified a problem but sometimes they can be funky. Pressure testing to 8psi and it holds same with the vacuum the problem is outside the motor of the saw. Fuel line, filter, impulse (understand it replaced), needle seat, diaphram, carb to cylinder boot, or carb circuits.