Stihl 038 Out of Gas

[Sam R]

It does, it's a complete rebuild kit, comes with all gaskets & diaphragms as well as needle, spring, lever, screen and I think it may even have welch plugs. Out of curiosity what am I looking for?

 

[HarleyT]

Examine the circuit plate diaphram closely. I had a customer bring me a saw once with a new kit already put in, and that was the problem, luckily he had kept the old parts. We put the old one back in, the holes were not in the right place.

 

[Sam R]

I'll be sure and look at each part very carefully against the existing part, thanks Harley.

 

[HarleyT]

Yeah, he insisted that he bought the kit from the dealership that I was working at, so I got it going "pro-boner"
Since the kit cost over $50 18 years ago, and Stihl sold the damn kit in a little snap-open plastic box, so the integrity of the kit was kind of suspect.

 

[Little Al]

The fuel tank is not pressurized it's vented to atmosphere if as soon as the saw stops if you remove fuel filler cap do you get a hissing noise it could be your "modded" vent I would check that 1st if OK have a look in the carb

 

[Sam R]

I ordered some of the OE spec grub screw vents I may go ahead and place them in there in place of the Echo style; which I put brand new in - the vent has been ruled out as an issue... And I guess you're right it's not supposed to be pressurized but it should be able to hold pressure.

An Harley yeah, I've been working here almost 4 months and I've heard some great ones already. *Guy complains of his 180-C throwing the chain constantly, when I point out the tensioner gear:* "Oh I don't think that does anything."

I've actually got the OE kit on order ($50, retail) and the Chinese knockoff, I'll compare them carefully and hopefully save the customer some bucks.

 

[Little Al]

I ordered some of the OE spec grub screw vents I may go ahead and place them in there in place of the Echo style; which I put brand new in - the vent has been ruled out as an issue... And I guess you're right it's not supposed to be pressurized but it should be able to hold pressure.

Iv'e always been of the understanding that if the carb end of the disconnected fuel line is lower than the tank fuel level fuel will flow freely from the line end & the tank is a vented container Can I ask how you think it gets pressurized firstly to then be in a position to hold pressure unless you are referring to a pressure test to check for leaks ,a vent would hold only a tiny amount of pressure a sawis only fitted with a gismo vent to enable large amounts of tipping & running awkward angles

 

[Sam R]

Yes, it was that. The tank was about 1/2 full, pickup fully submerged, In my experience working on mainly more contemporary saws the fuel will always pour out of the disconnected hose, that's where I got pressurized from. There must be a small amount of positive pressure inside a capped tank in order for that to happen. I didn't know for sure whether that would affect running but I thought I'd include it for the sake of posterity. Is a gismo vent the echo style?

 

[homemade]

Don’t forget. The grub screws get pushed into the hose. Don’t screw them in.

 

[Sam R]

Don’t forget. The grub screws get pushed into the hose. Don’t screw them in.

Good to know. These style vents are older than I am and I've always hated working with them. This particular saw had no vent just a little saw dust sucking hole on top of the tank.

 

[homemade]

Good to know. These style vents are older than I am and I've always hated working with them. This particular saw had no vent just a little saw dust sucking hole on top of the tank.

Yeah, if you screw them in they cut threads into the hose and make a seal.

 

[Sam R]

What's the deal with there being two of them? Is that for some added efficiency?

 

[HarleyT]

Yeah, if you screw them in they cut threads into the hose and make a seal.

Is that how baby seals are made?

 

[Sam R]

Update on the 038: Rebuilt the carb, the inside of it was totally nasty... on the screen side. So the screen did its job well, cleaned it up real good, blew it out with the stuff and replaced everything from the kit, matched all gaskets and diaphragms - only thing I didn't use out of the Chinese kit was the inlet spring which was quite a bit longer than the existing...
Saw now runs 100% better but it's still pretty hard to adjust, got it tuned about right to where it'll rev up quickly to about 11500 (seemed to be the sweet spot, turn it higher and it's too lean it'll bog down before revving) and got it idling almost exactly on 2800 -- only thing is when you come off the throttle - warm saw - its idle will drop to about 2100 for awhile and work its way back up to normal. Didn't die when I did this just a weird thing it was doing. I'm open to ideas on that; but my guess is it's still in the carburetor. Maybe that new spring had enough tension, I dunno - the customer wanted it today so he could cut some wood out in his 100 acre wood and so I told him all this and to bring it in if it gives trouble.

Couple other interesting things I learned of this saw: he was running it on a 100 degree day and was using 50:1 mix in it, pretty sure I know why it fried. Scoring is of course concentrated on exhaust but there's a bit around the intake too. Air filter was dirty and the fuel filter didn't look great either.

I did 2 top ends this week and I've got to say of the two kinds I know to exist, clamshells are much easier to work on.