Hi,

I'm a weekend mechanic when it comes to small engines. I can do a few things, but can also mess up.

I have a Stihl chainsaw that was running ok in the fall with the exception of starting poorly when hot. I took it out for its first spring action and it turned and then wouldn't start. So I squirted some small engine carb cleaner into the carb and some starting fluid into the air cleaner. Now it starts up fine and will continue to run on idle or a medium throttle, but if I pull the throttle button fully, it dies no matter what I do.

I've looked at a few threads from the past and they all point to carburetor problems. This makes sense to me, but I'm not sure I can take this thing apart and put it together correctly (I've rebuilt two carbs in the past from small engines, but it was a long time ago). Any suggestions? How hard is this to deal with? Am I best taking it to a repair shop and paying a lot (for me) or is this some thing I could do myself?

Any feedback would help.

Thanks,
Ian K

 

You have a carb issue or a fuel line or filter. Removing, cleaning, and putting a kit in will likely take care of a carb problem.

It could have a vacuum leak somewhere along the intake or at the crank seals - the latter being a little more involved to fix.

I believe I would try adding a little Sea Foam to the gas oil mix, let it run for about ten minutes, without a load, then shut it off and let it sit for an hour. Then start it up and see where you're at. You may have to adjust the low speed mixture to fine tune it.

If the problem persists, think about the carb work. On a scale of 1 to 10 it's about a 6 in difficulty. Just lay everything out as you take it apart and assemble it in reverse if you decide to do it.

 

Wow. The Seafoam worked miracles. The engine now runs more smoothly and it also runs at full throttle. I haven't tried cutting wood with it yet, but I'm assuming it will work.

Marbobj, your comments saved me from doing or paying for a lot of unnecessary work and the grief attendant to worrying about problems that I didn't understand. My gratitude is without measure, and I've got the Seafoam ready for my other small engines that have not been serviced for years. Thanks.

 

That's good news.

You probably had a little varnish in the carburetor and the Sea Foam took it right out. On older engines sometimes you get stuck with installing a kit - diaphragms get stiff and additives can only do so much.

Take care

 

Just be sure that the saw is getting enough fuel. It can seem to run well and still not be getting enough, which will ruin it. Make sure the throttle response is crisp with no lag and the engine flutters a bit at full throttle instead of screaming high rpms.

 

I have a new still weed trimmer; it would not start at the end of last summer. Still under warranty, the local bob's cycle and equipment said it was the carburetor and they would not stand by the warranty. They said it was my fault for using oil/gas that had sat for two months. They said it should never set over one month. I complained to Stihl corporate, and they honored it. Is Stihl oil/gas mixture that sensitive?

 

If you used Stihl oil and the gas was fresh when you created the mix it should last 6 months or more, the Stihl oil has stablizer in it. However if you started with old gas it is going to have problems. Have a good one. Geo

 

You in Vestavia, treeves?