Saw start up difficulties

My 038M seems to require an excessively rich set L (2 turns out) to get it to startup, but then it won't stay running until I get closer to 1 turn out. Once running, I dial in the L and it is happy around 1 turn out. Go cut wood, power is there, saw runs great.

The next week, rinse and repeat. Won't start with 1 turn out, needs a rich start, blah blah blah.

I am going to clean out the carb again. This will be round 3. I rebuilt about 2 years ago when I did the mag conversion.

Any thoughts on what to look into besides carb?

 

What's the compression running? Below 120 lbs, a chainsaw is sometimes troublesome to start.

 

I am going to check that this week. My gauge is not very good, but the saw seems to have a good amount judging by my shoulder. It was set at .020" squish.

 

Check to make sure the choke in the airfilter is staying closed

 

Yes - the choke not closing all the way was a common problem with that era stihls

 

Compression is there as expected, 3 pulls I was at 160 and climbing on my junky gauge which has always measured way low.

Choke is working, I replaced the master choke lever and the spring still has the force to keep it closed.

I will do a carb cleaning again and report back. I did replace the fuel tank vent with some fuel line and I stuck the check valve back in the end... could I have screwed something up there? I don't think so seeing as once its running all is well.

Thanks for the help. This was gonna go on the trading block once I put some tanks thru it... might be a discounted price if I can't figure this out soon.

 

OK so sadly this is still an issue. I soaked the carb overnight in carb cleaner, and put it back together. Started right up no problem.

A couple weeks later, same darn thing. I was going to put this up for sale, might have to sell it is a "good runner.... when it starts" and lose some money on the deal.

 

Try another carb. Even if its used off a known runner or cheap china ebay carb if available.

 

Try raising the lever that operates the metering needle. If you raise the part of the lever where the diaphragm hits it that will richen it up some. It does not take much and sometimes is trial and error.

 

It's plastic Good thought though

 

While I was attempting to clean my shed last night, I tried the saw 1/2 turn out richer. Fired right up.

Going to let it sit and see. New carbs are $40+

 

Your kidding, I have never seen a plastic lever inside the carb for the metering needle. What kind of Carb is this.
I want to look this thing up.

 

It's a Bing.

 

I think I would get a different carb. Did they use Zama or Walbro carbs also.

 

Or a Tillotson.

 

I believe Tillotson but have to see if that works on the mag

 

Sat overnight, fired 2nd pull this afternoon. Tells me a few things: choke is working fine, once the line is primed its good to go.

So maybe this thing just takes forever to prime after sitting for long periods of time? Your metering lever suspicion could be correct.

 

Does it have a pin hole some where that allows it to loose prime quickly?