Dies on throttle up

[Frax]

A number of saws that usually run well are suddenly a pain to throttle up. Some of them I can get past the problem by goosing or coaxing the throttle until it gets to full speed.
A couple of others just aren't playing at all. They start but won't throttle up. They just die.
They are all getting Trufuel and are cleaned up and out regularly.
I'm wondering if it's because of the extreme humidity and heat this week. They come inside the air conditioned house at night. Is there condensation in the carb?

 

[oldoakman]

They have a head cold frax. Give them a shot of whisky.

 

[Leroy]

Sounds like a heat issue, we have the same problem with some of our saws.

 

[Frax]

They have a head cold frax. Give them a shot of whisky.

That'll be for me!

 

[Nish]

Hello Frax. If you find a reliable saw mechanic anywhere near Chapel Hill, I'd very much appreciate the contact info. (I have a ms150 doing what you describe. It's been in the been in one shop for most of this year. The Stihl dealer sent it back to me twice; after using up the Sea Foam their mechanic put in its tank, the problem immediately reappeared.)

 

[Tom Dunlap]

Do i understand...

Saw will idle but when you pull the trigger for high speed it bogs and cuts out??

In the 'old days' when we could adjust carbs this was a symptom of a lean low mixture. The cure was to open the low speed jet a little at a time. i would use the width of the screw slot on the jet as a guide. in half-blade increments i'd open, counter-clockwise, the jet. Low speed is lower, closer to the cylinder.

The purpose of the low speed adjustment was to act like an accelerator pump on a car carb.

When the saw idles it only needs a low amount of fuel/air to idle. When the throttle is opened more air is sucked in leaning out the mix momentarily. Giving a little bit more fuel for that moment richens the mix until it runs on the mix set by the high speed jet.

Since there are less and less adjustments available this tuning might not work. At one time you could take a snip and break off the plastic caps on the adjuster. Or, buy the factory tool to remove/replace them

i'm sure that you're keeping air filters clean and blowing out gunk from around the cooling fins. Basic tidiness.

 

[96coal449]

I was in the tree once and had the same issue. Sent the saw down and the guy I was climbing for said it was afraid of heights.

 

[Treezybreez]

I had a power head come loose because a screw was missing. The saw would start but it would not idle for long and it would die when I throttled up.

 

[craneguy1]

We've been replacing carbs left and right for about 3 years now...clears up the symptom you've described when everything else checks out good...that and no top end when you stick it in the wood. Screw rebuilding them...time is money.

 

[Kevin]

Is the spark arrestor plugged with carbon?

 

[r0ck1r0ck2]

carb cleaner, spark arrestor, fuel tank vent, fuel tank filter?

check the plug?

just my dirty .02¢

 

[RajElectric]

I have a 192 doing that to me, filters, plug, seafoam, good cleaning would temporary fix it, but would still bog down. Finally took the carb off and took it apart, cleaned it, back to brand new.... for now.

 

[Fl cracker]

Agree with the carb thing,i used to have luck rebuilding carbs. The ethonal is reason i think they wont rebuild anymore. I throw them away buy a new carb.i had an 020t do thus to me last year drove me crazy i finally took carb off that only had a low speed jet adjustment bought a carb that fit it with a high and low jet put it on and runs luke a.brand new saw