1988 024 Stihl Loss of Power

Dietch3

Hi all, I'm a newbe. Hope all are well. This is a great site!!

Well here's the problem. This saw has been awesome until about 3 months ago. Started dieing on me after about 25 seconds of use like it was out of fuel. Now, I never rebuilt the carb or changed the plug in 21 years. Started with the plug first. Still the same however if you turned the saw upside down and shook it it would restart and run for about 20 seconds and die. So I rebuilt the carb. Started great and ran 1 full day of cutting. A week later go to use the saw and the same problem occurs. So , I change out the fuel filter and a new line. Appeared that no fuel was getting to the plug as it was dry. Would not start. Turn upside down and shake--it starts and runs for about 20 seconds and dies. Compression is good. I'm totally bummed--any suggestions?

What I did notice was that the new fuel line is hourglassed about 1/2 way down. But it was new that way.

Thanks.

Bruce Hopf

Have you checked the air vent, at the top of the fuel tank? Have you cleaned the air filter?
When you were running it, did it just stall, or did it gradually just run out of power?
I would start, by looking at the vent for the fuel tank. It could be plugged.
Also there could be a hole in the air intake line, that runs from your carburetor to the cylinder.
Also have a look at the impulse line, which is the small tube, that is underneath the air intake line. Bruce.

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Dietch3

Thanks Bruce,

The vent to the gas tank is not clogged. The other ones I have to look at. The air intake is clean --will get back shortly.

The saw gradually dies but if you turn it over and shake it comes back as it is dieing.

windthrown

Sounds like a bad impulse line to me. Or a leak in the carb to manafold seal (amounts to the same thing, really). Make sure that the carb is bolted on tight or there may be a leak in the intake seal. It could also be a bad crank seal leading to more air getting into the lower crank area of the engine (though that is less likely).

Overall though, I would guess that its a bad impulse line. A pain to replace, but critical. I have replaced many of them on older saws to resolve bad idle issues, and racing or stalling saws. A warning about running a saw for long with any of these leaky air intake conditions: the saw will run lean. Running lean mix saws can lead to scored engines.

Also check for leaks in the gas line. Stihl saw gas lines can commonly fail after a few years with small cracks, and they are hard to start and they will not run with gas line leaks. Also pull the muffler and check for a scored engine. I have known many saw mechanics to look for all kinds of stuff and tear down the carb, swap out lines, and only later find that the engine is scored. Also while you are pulling the muffler, check the spark screen. If they cake up, they cause engines to run like crap, just as if all kinds of other problems are an issue. A simple muffler screen cleaning can make an engine run great again (they run way rich and choke up).