Scratch the changing of the fuel tank vent from my to do list. I took the bar off and turned it on it's side and removed the fuel cap. It would not start.
Stihl 038 Woes
- Thread starter djg james
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Check the intake boot/manifold it was torn 3/4 the way on mine and it had the same problems, that's the rubber boot that goes between the carb and cylinder.
When I change the gas tank years ago, I had trouble getting that boot to seat right. Finally did. I visually inspected it before I posted today and it did look seated, but I couldn't see all around if any cracks were present. How do I get to the boot to replace it? Have to take the tank back off?
It's a real PITA, but my stihl dealer missed it even I couldn't tell till I took it off. Yes the best way is to take the gas tank/handle assembly off to access it.
Mine tore next to the cylinder, so you can't really tell unless you take it off. I get aftermarket parts from either sawzilla or wolf creek FYI.
Rebuild the carb using a good kit preferably from the manufacturer, not a chinese knockoff because the internal parts like the needle/spring/spacers/screens are not the same quality and often do not match perfectly in thickness, dimensions or lack in quality of the materials. Your issue is likely in the diaphragm or fuel pump being hardened or deformed.
If you need a good used boot I have a couple or they can be sourced still on fleabay
I'm hoping to eliminate everything else before I tackle the carb.
Ive got a new one, if you can't find one. I got mine from sawzilla.
These carbs are pretty easy to rebuild, you can even get brand new tillys for these still
OH_Varmntr
Burner of stored sunlight
038s are known to have issues with the choke flappers not fully closing off the port in the filter causing starting difficulties when cold.
I'd start from scratch when it comes to a saw that has hunting issues. Pressure/vac test the saw and check rubber components for air leaks. Intake boots can be cracked but the cracks don't open up and leak air until you flex the boot. I've seen where saws run fine out of the wood but when you bury the bar and lean on the saw, the boot flexes and opens the crack. Air leaks in moments of high engine loads like this are a great way to toast a saw.
Maybe I'm a purist, but I wouldn't trust any AM parts (Meteor pistons are my only exception), especially carbs and rebuild kits. OEM parts are available through ebay and your local dealer.
Air leaks first, then fuel, then spark.
I'd start from scratch when it comes to a saw that has hunting issues. Pressure/vac test the saw and check rubber components for air leaks. Intake boots can be cracked but the cracks don't open up and leak air until you flex the boot. I've seen where saws run fine out of the wood but when you bury the bar and lean on the saw, the boot flexes and opens the crack. Air leaks in moments of high engine loads like this are a great way to toast a saw.
Maybe I'm a purist, but I wouldn't trust any AM parts (Meteor pistons are my only exception), especially carbs and rebuild kits. OEM parts are available through ebay and your local dealer.
Air leaks first, then fuel, then spark.
First thing I do when I get a saw with a blown top end- vac- pressure test, saws don't usually wake up one day and say I think I will retire and blow a piston- last week I got my answer pretty quickly by empying the gas tank on a 440 I built for a guy- no mix- guess I had put enough of my own gas in it lasted that long untill he filled it, used the wrong can I guess, mine are clearly marked
I bought a gauge for pressure/vac testing back in January. Just haven't used it yet. I'll read up on how to use it and test the saw in the next couple of days.
As to running, the thing you don't mention is the "pump side" of the carburetor. Those diaphragms can stiffen from ethanol in the gas, etc. needle valve can clog... Assuming you have impulse from the impulse line, the next thing between there and having fuel in the cylindrical is the carburetor. Most likely next place to look.
As to losing fuel from the tank, you can empty it and then gently put a little air in it do dish soap a la looking for leaks in gas plumbing (or you can even put sections of the saw tank end in water looking for bubbles....)
As to losing fuel from the tank, you can empty it and then gently put a little air in it do dish soap a la looking for leaks in gas plumbing (or you can even put sections of the saw tank end in water looking for bubbles....)
My first question is where is the fuel going when 1/2 a tank disappears when setting? Is it flooded?. It has to be going either inside or outside.
That is where we start.
That is where we start.
I haven't figured that out yet. I don't see any leakage on the outside. I store the saw in a tray. No liquid.
might be the carb not holding pressure and going into your engine crank case- is the plug wet- you can pressure test a carb by taking it off and pumpig in 15-20 lbs positive of pressure into the fuel inlet if it doesn't hold it at 15 forever then that's a problem- ps- try to get as much pressure out of your tank - better yet empty it before removing it and have somethig to plug the gas line- i have a pile of plastic plugs for that purpose
OH_Varmntr
Burner of stored sunlight
You'll also have to make a couple of blanking plates to block off the exhaust port and the intake. There are plenty of videos and threads on the subject but we are here if ya need help.
You find some really interesting things the more you tear into these things....
OH_Varmntr
Burner of stored sunlight
The 038's have a .68L fuel tank capacity which is around 23 fluid ounces. So if you're losing around 12 ounces of gas into the engine you'd be able to find it.
You may also have a gas-guzzling family of gremlins living in there...
I tried a few more things this morning. I noticed a small crack on the impulse line in a spot that was covering the top fitting. Didn't think that was the problem, but thought it might develop into a full tear, so I changed it. Didn't help. I noticed gas oozing slightly out of the gas tank line when I had the cap off.
Thought maybe the gas tank vent was plugged, despite previously gas coming out of it when the saw was tipped on its side. Changed it.... no help.
When I had the carb off, I pressured the intake manifold boot to the point where it bellowed out slightly and hit it with soapy water. Could not see any bubbles.
So now I've got it back together, filled up, on a clean oil drip pan and am watching for any fuel leaks. It'll prove I wasn't dreaming.
Time for a pressure check. Haven't had much indoor time in front of the computer so I'll do a search now.
Some of you mention OEM, Tillson or Zama carb kits. Where do you get them?
Thought maybe the gas tank vent was plugged, despite previously gas coming out of it when the saw was tipped on its side. Changed it.... no help.
When I had the carb off, I pressured the intake manifold boot to the point where it bellowed out slightly and hit it with soapy water. Could not see any bubbles.
So now I've got it back together, filled up, on a clean oil drip pan and am watching for any fuel leaks. It'll prove I wasn't dreaming.
Time for a pressure check. Haven't had much indoor time in front of the computer so I'll do a search now.
Some of you mention OEM, Tillson or Zama carb kits. Where do you get them?
