Strimmer problem

[Wilko]

 I have a Stihl strimmer which runs on an oil and petrol mix....is that what we call 2 stroke in the UK ? Anyway it has worked beautifully for the past 4 years. A couple of days ago it refused to start...........it was kinda backfiring all the time when trying to start it. I borrowed my neighbours strimmer to finish the work and then refilled his tank with my mixture.........he popped round this am to tell me his strimmer wouldn't start. He thinks that the mix is the problem and says that he thinks that the mix deteriorates over time causing the starting problem. Anyone have any experience of this situation ?

regards

Wilko

[Chancer]

No but I had the ignitin module fail (very, very common) with the same initial symptoms, have you tried starting your or your neighbours machine with a fresh mix?

I hope that his module hasnt chosen to fail at the same time!

You should always drain the reservoirs of all 2 stroke machines at the end of the season and run them until they stop, gunge can build up during the idle period causing similar problems to yours on initial start-up (something until recently I was ignorant of) was this the first time this year that you used the strimmer?

[Pierre ZFP]

Yes the mix will deteriorate over time and not much time at that.

In warmish weather it can go off in as little as 3 weeks. 

I had a 2-stroke chainsaw that would absolutely refuse to start unless it had freshly squeezed juice in it.

[Anton Redman]

Normally have to discard then remix fuel for chainsaw if it is left over winter. You can I believe buy additives which may help. Last local garage which mixed two stroke closed this spring.

[Wilko]

Hi Guys

Thanks for the replies. I will try with a fresh mix tomorrow.

Rgds Wilko

[Scooby]

Definitely deteriorates...and deteriorates quickly.  Worth looking at the spark plug as well...a clean or replace may be in order.

[Chancer]

The strange thing is untill I knew about the gunging problem I always used to leave the fuel in my 2 stroke machines over winter and in one case for more than a year, mind you that is when the ignition module went, now technically speaking there can be no connection but on sait jamais.

My disc cutter sat for over 2 years with stale fuel in the reservoir and restarted normally.

What is the actual deterioration in the fuel mix, a lack of lubrication, gunging up or something else?

[Anton Redman]

I believe the more volatile/lighter parts of the pertrol evapourate so it becomes harder to start.

[DerekJ]

btw, depending on which model you have you may find you have what Stihl call a 4-Mix engine.

This is basically a 4-stroke engine that uses 2-stroke premix oil/petrol.

However, you say you've had it for 4 years and I suspect that that was just before Stihl introduced the 4-Mix engine.

[BIG MAC]

Yes all fuel goes off but rarely in the fuel tank unless its nearly empty.Think about it the vapour needs to go someplace and it will take quite a while for it all to escap vie the pinhole vent!

What generally happens is that  the mix clogs the float bowl and the jets in the carburettor.

What can you do?

Switch of fuel if you can and run until the motor cuts out after use.

Shake the machine to agitate mix, remove drain screw from floatbowl and allow rubbish fuel from line to run through, replace screw. Remove air cleaner (Sponge pad usually in a small cage or similar) Squirt some aerosol carburettor cleaner into the inlet trumpet (Careful if this gets in your eyes you will know all about it) after a minute or so turn the motor over will the pull start (Ignition in off position) to clear the carb cleaner, prime the carb and start normally. Run at a fast idle for about 3 or 4 minutes before working the machine.

[Chancer]

Thanks BM, that makes more sense than some of the old wives tales, I have some neighbours that will throw away 2 stroke mix from a full sealed container if it is more than a couple of months old, they also wont mix fuel but instead buy their fuel pre-mixed at a stupid price from the lawn mower shop because it is much better.

Of course the source of their superior knowledge is the patron of the shop [:)]

[BIG MAC]

Hi JR It's the expertise born of years of two stroke ownership, skinned shins from them hitting the footpeg while trying to start a cantankerous Kawasaki kh250 (in the middle of a Scottish winter) and knowing in the heart of hearts that no amount of redex was going to replace the labyrinth seals, but the pink smoke rings were impressive!

There is one fuel additive that works better than most.......common sense.....pity it isn't that common!

I have a sneaking admiration for said shop proprietor...I know it's wrong but it made me chuckle!

[Chancer]

[quote user="BIG MAC"]

Hi JR It's the expertise born of years of two stroke ownership, skinned shins from them hitting the footpeg while trying to start a cantankerous Kawasaki kh250 (in the middle of a Scottish winter) and knowing in the heart of hearts that no amount of redex was going to replace the labyrinth seals, but the pink smoke rings were impressive!

[/quote]

My god that takes me back, I never owned one but used to lust after one that another apprentice owned, the memory of the sound, the smell and even the taste of those smoke rings when the throttle was blipped is as strong as ever.

But mixing in Redex! - thats just plain kinky, real 2 stroke porn, I will have to buy one one day to experiment.