tree removal - chaisaw problem, wrog fuel mix

[clemsonfor]

Why even keep any 25:1 pretty much anything with that ratio can run on 50:1 . That old ratio was for use with sae30 oil. Modern oils lubeuch better. I would get rid of the 25:1.

I don't think you have a problem. Put like 1 oz in the fuel tank and fill with 50:1 and run through a whole tank. I bet it clears up.

 

[clemsonfor]

Thanks. Would scoring of the piston cause the issues I'm experiencing? It seems to run fine at other speeds, but dies when given full throttle. Though yesterday I got it to run almost normal for a few minutes then start doing it again and now it stalls pretty much immediately. I'll take a look in the cylinder today and see what it looks like. This is a pretty old saw (90's vintage), so maybe that something else just decided to fail finally VS having anything to do with the fuel - though that's unlikely.

Thanks. The saw was running perfectly before I put the wrong fuel in (like 2 minutes prior), so the only variable is the fuel. It had actually just been tuned up and has gotten regular use. I haven't checked the fuel line and filter (requires more disassemble), though that is probably the next stop. Thanks for the offer to look, I'm NW of Boston. I'll probably drop it off at my small engine guy if I can't figure it out today, he's pretty good and familiar with the saw.

I did check the diaphram, which looked ok. I was afraid it got gunked up with the oil. The saw didn't sit at all with fuel, so while I agree ethanol is evil stuff it probably isn't to blame here. I did put brand new higher test gas in it yesterday just to 100% rule out the fuel itself and had the same issue.

Score. Pistons will cause all kinds of problems. Not ideling, hard starting , no power. Depending upon severity. Just pull the muffler. Its not hard.

 

[tractchores]

Score. Pistons will cause all kinds of problems. Not ideling, hard starting , no power. Depending upon severity. Just pull the muffler. Its not hard.

Thanks per my above post i did, no scoring.

 

[GGB]

I had the same problem with my larger Stihl weed-eater, and finally took it to a local Stihl shop. As I suspected, the high speed jet was dirty, and that was even after premium fuel and only using silver Stihl premix. it was time for a service anyway, so no big deal. Well worth the $65 they charged to service and clean.

Since then, I've gone one step further and now use racing gas to try to eliminate any ethanol contamination issues. So far, so good.

GGB

 

[RalphVa]

Unbelievable that the saw motor is so sensitive. I never paid any attention whether one engine used 40:1 or 25:1. It'd just mix up 40:1 and use in all. (think this was among the Stihl, Craftsman and a grass whip engine. One of them required something different.). I put chain oil in the gas compartment once on my Stihl 009L like luvmexfood did. Just drained it out with saw upside down. Put new fuel in, and it ran fine since. Did same thing on a Craftsman. Never could get it to run again. Gave it to a friend who's good with repairing stuff. He got it running and is using it. After that, I painted the oil cap blue and the gas cap red on both machines.

 

[BukitCase]

Here's one nobody's mentioned (I think) - one of my Stihl saws a few months ago had similar symptoms, tried most of what's been mentioned in this thread - no help.

Finally noticed that the fuel pickup tube's filter end (right next to the filter, AKA counterweight :=) looked a bit flat - pulled the whole tube out of the tank and it was "squishy", more than seemed normal. Stopped by local Stihl dealer, bought new one, installed, problem gone. Apparently the added suction of high rpm's was enough to finish flattening out the pickup tube. Freakin' Ethanol.

Can't express enough how much I hate "congressional gas", been using hi octane "E-0" ever since... Steve

 

[haveissues]

I bought a erratic running Stihl ms280. One minute it was fine, next minute it had no power or idle then back to running fine. Turned out the intake boot had a split in it. At $75 it is one of my better purchases. If you have compression and the carb is fine I would say you either have a fuel line problem or an air leak.

 

[tractchores]

I think the fuel lines were replaced when it was tuned up about a year ago, but am not certain. Given that it's only a few inches long and the cost is minimal that is probably one of the first things I'll have them replace as well as checking the vent. My money is on a fuel delivery issue, so mine as well start with the small and easy stuff. I also didn't love the look of one of the diaphragms (seemed like the edges were separating a bit). If that fails then a replacement carb is probably next (it appears they are all one piece and not serviceable unless I missed something). Taking her in on Friday to see and will keep everyone posted.

 

[ljnelson109]

This is a long shot, but I will add my experience. I have a cheap craftsman saw. Kept having problems with what seemed to be no power at all. I played with fuel, adjusted carb, etc. At one point, I played with the chain tension. It seemed if the tension was looser, it would work better. I realized that the chain seemed to be gummed up some. Sprayed bar and chain with a solvent and it ran/cut better for some time. I finally figured out that the bar oil I was using seemed to have gone bad. I threw that away and used a new can of oil. It seemed to be gumming up the chain and bar. And being an underpowered saw, it was enough to give me the impression that the motor had no power. Needless to say, I was surprised at the cause. 2 cycle engines don't really have torque. They need to spin up, and with too much resistance that becomes a challenge.

 

[tractchores]

Thanks everyone for the advice. As suspected it turned out to be a fuel problem. There was an issue with the fuel hose not supplying enough fuel at high RPM, with that and the filter replaced its back as good as new. I just got it from the shop today. Pretty annoying to have to redo the fuel line after only 1 year, but I guess that's ethanol for you!