# 2-stroke engine idle problems



## Joel_BC (Aug 5, 2015)

I've owned many 2-stroke machines - chainsaws, weed whackers, portable water pumps, etc. All sorts of brands too (for instance, Stihl, Homelite, Shindaiwa, others). This problem has plagued me again and again. Warm, but not overheated, engine dies easily during idle.

When the machines are brand new, or have had a complete carb cleaning and standard (kit) rebuild, the problem isn't there, so long as the engine has been warmed up, fuel mix is correct, air filter has been cleaned recently. But I myself, and a lot of guys I know, are frequently gunning the engines between applying power to the work at hand, to keep them from dying.

Right now my weed whacker wants the idle screw set much higher than, say, four months ago. A lot of the carbs now are _only_ adjustable in terms of the idle setting.

I know that a good fuel delivery situation depends on multiple factors, such as good/clean fuel filter, clean & intact fuel line, clean carb throat and throttle valve, clean small-passages within the carb, diaphragm in good condition.

What things (and _in what order_) would you check when trying to improve this kind of situation? Thanks.


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## Joel_BC (Aug 5, 2015)

This post has had 77 views, but no responses yet. So I'm thinking the I may have made the question a little too detailed!

Simpler way of asking it: if the warmed-up engine dies while idling, what aspects of fuel delivery would you check-out first? second? third?


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## SABL (Jul 4, 2008)

Hi Joel,

The number of views has nothing to do with the details of your original post and lack of answers. Many others (including guests) may be looking for the same answer. We do have members that are competent small engine mechanics but they may not have seen your thread yet.

I can offer no suggestions.......the least amount of dealings I have with 2cyc the better.......:laugh:. I have two commercial Echo trimmers that still idle....even after many years of use.


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## AVB (Nov 28, 2014)

It all depends on the equipment condition. As equipment ages it develops air leaks in the fuel system which includes the crankcase that normally affect idling first and at other times it is full throttle that affected. 

Things like metering levers not set correctly or badly worn can fuel mixture problems and even quit opening the metering needle at idle if out adjustment enough. Worn crankshaft seals, bad gaskets, warp carburetor adapters, and loose mounting bolts are also trouble makers. In these case it takes an experienced 2 cycle repairman to find these problems and sometimes it even drive us nearly crazy.

This is not something that is simple to repair most times. I have spent a whole day to find simple air leak.


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## Joel_BC (Aug 5, 2015)

AVB said:


> It all depends on the equipment condition. As equipment ages it develops air leaks in the fuel system which includes the crankcase that normally affect idling first and at other times it is full throttle that affected.
> 
> Things like metering levers not set correctly or badly worn can fuel mixture problems and even quit opening the metering needle at idle if out adjustment enough. Worn crankshaft seals, bad gaskets, warp carburetor adapters, and loose mounting bolts are also trouble makers. In these case it takes an experienced 2 cycle repairman to find these problems and sometimes it even drive us nearly crazy.


Thanks, AVB - very informative. These sneaky air leaks probably generally contribute to a leaner fuel/air mix, right?

Made me wonder about using something like Seafoam. I don't use it very often with any of my machines. Maybe every two years (at most). But it seems to me that if it clears away gunk from the carb's passageways, it may also clear gunk away from spots where air wants to leak through - spots like the ones you mentioned. So is Seafoam a bad idea?


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## AVB (Nov 28, 2014)

Never tried the Seafoam so I no experience with it.

But I would think cleaning gunk away from spots where air wants to leak through would just make them leak more.


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## alpenadiver (Jul 31, 2007)

I use Seafoam on all my small engines, everything I store gets seafoam ran through it, never had a issue. Gas with Ethanol, will cause problems because of the Alcohol, it will dry out rubber fuel lines, o-rings, and cause a build up on the inside of the carb.


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## Basementgeek (Feb 7, 2005)

I too use Seafoam in everything.

I have found that my couple of 2 cycles seem to run a little better with some better than regular pump gasoline, I use like the middle grade for them.

BG


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## Roymg (Jul 13, 2009)

I've had many sessions with Stihl 2 cycle grass trimmers carb problems. Seems like the ethanol gas caused some replacements every couple years of the China carb, that I understand that Stihl now owns. I run mid grade gas in the units (I have 2). So I was replacing the carbs every couple years. I have even tried the rebuilding route. Now what I do if I have problems getting these machine to run right I take off the carb and let it soak in gas. Seems to have taken care of my problem.

You should not leave gas in these 2 cycle engines after the season is over. If u do use Sta-Bld, but next season soak'em (carb) n gas.


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