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Storage of 2-Stroke Power Tools

Started by kevinthelawnmowerman, July 25, 2021, 05:24:06 PM

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Hi Everyone,

I am looking to get your views on the best way to maintain the condition of the carb diaphragms as I have noticed that some machine manufacturers recommend emptying the fuel tank and then pumping the remaining fuel out of the carb with the primer, and then emptying the tank again. But, I have noticed that the diaphragms in Stihl machines fitted with Zama carbs seem to have an adverse reaction to running them out of fuel and leaving them dry. The metering diaphragm becomes wrinkled and saggy after only 2-3 months. Has anyone else had this happen?



Bit of a grey area this one.  ;)

Most recommend you run dry before storing your machine. Companies such as Stihl recommend you don't use (Pump) fuel more than 30 days old because it goes off.

I've used fuel left over from last year without any issues whatsoever in my own Stihl strimmer.  So again that's not an exact science.

I think the rubber coatings n Diaphragms and rubber used in fuel hoses reacts differently when it gets old. When used with pump fuel for a long time then dried out over winter. You introduce fresh fuel and notice things are turning putty like. Worse still if the machine sat with stale fuel in it.

Then you have engines that have run since new on pump fuel, then suddenly switch to Alkylate, as in Aspen, MotorMix etc, you then discover the metering diaphragms go stiff like cardboard.

There's just too many variables while using and storing this gear.. I think some of it comes down to luck.


Hey Mick,

It does seem to be a grey area indeed.

I have seen so many mowers, strimmers, brushcutters this year which won't start because the fuel has gone off. I suggest to my customers that they use a fuel stabliser such as Fuel Fit as I use this product and don't have a problem. One customer did try and mix the Fuel Fit in the tank of his mower..............!

I have also had quite a few machines which won't run because the metering diaphragm has become stiff and in all cases fuel has been left in the carb.

With a lot of the tools made in the PRC the fuel hose actually dissolves in the tank and falls apart.

I guess one day a pattern will emerge that will dictate the best practice.