Petrol Strimmer - wont fire

[msmbus2000]

I have http://www.argos.co.uk/static/Product/partNumber/7300961.htm

great strimmer when it works it has went thru 3 pull starts in the past 2-3yrs wouldnt mind but its not used that often and now the machine will not fire up.

No spark at the plug - so its down to either a bad plug or coil (coil is only around £19). Is there anyway I can test the coil?

Cant get a new -plug until tomorrow as nowhere local thats open today seems to have them - and b&q well worse than useless

Marty

 

[Debs.]

Check the cut-off (start/stop) switch before buying anything; if it`s faulty/stuck/'grounded' then there`ll be no spark.

 

[msmbus2000]

Checked the switch there, its working fine - sods bloody law lol

 

[PTvor]

You can check whether the secondary of the coil is open circuit with a meter. If it is, it's new coil time.

You might have a bad HT cable or a short to earth in the HT line possibly caused by dirt or a bit of grass. Is this strimmer damp? It shouldn't matter too much, but you never now. Mine lives in a dampish garage and starts in the Spring with a bit of trouble. It's 20 years old.

Look for bad and corroded contacts on the low tension side. Loosen them, clean them up and retighten them. Bad contacts cause all sorts of problems.

It's worth heating the electrodes of the old plug in a gas flame tor 10 seconds or so and trying it while it's still warm, it doesn't have to be hot

 

[tigler]

The clue is in the comment, 'not used much'. Fuel goes off if left standing and causes difficult or non starting. That may be unconnected with the immediate problem but could be why it's gone through so many pull starts.

 

[cazl1994]

pour some fuel down the plug?

 

[msmbus2000]

I will get fresh fuel & 2 stroke oil tomorrow when I'm out getting the new spark plug.


I will give it another going over tomorrow.

Thanks again for your input :-)

 

[R Kraft]

The old fuel gas mixture will foul the plug quickly.
Even if you dump fresh mix in the old fuel.
Robert

 

[bill_gj]

My strimmer is quite sensitive to the 2-stroke mix. Too much oil and it's a right b!tch to get going. I got it second-hand (but very little use) and first assumed that a 20:1 would be OK, but it needs to be much less oil than that.

 

[PTvor]

The tech at the Stihl agent told me that the mixture ratio is definitely a property of the oil not the engine. Stihl 2 stroke is 50:1, a lot of others are 40:1. Too strong a mixture and you gum the rings and cause problems.

I'm sure that back in the day when SAE30 was used as 2 stroke oil it had to be made richer.

However, another reason why 2 strokes which have been left a long time are hard to start is that the petrol evaporates off leaving a mixture containing much too much oil.

In this case, there isn't a spark at the plug, so problems with the fuel apart, that needs sorting first.

 

[Dune]

I think some of you have hit the nail on the head. Strokers like between 40 and 50 to 1 oil in the fuel. Anything more than that and they can be a pain to start. Gumming is also common on strokers. Try running some redex through it when you do get it going.

As for the coil you should be able to get a meter on it one side should read under 1 ohm is and the other very high say 10k Ohms plus. Next is inspect the HT lead. Any cracks in the insulation? Hows the plug cap? The cap and the lead should be under about 10 ohms.

Next thing is your spark tigger. How does it know when to fire? There will be something that travels past something else and allows the spark to happen. This may need cleaning or changing.

Oh and when you do get it working before you put it away cover it in WD40!

 

[PTvor]

For 2 stroke oil, buy a decent brand and mix it the way it says on the bottle, don't try to second guess the maker's R&D dept.

Don't use 2 stroke oil for outboards because you have some lying around, it's different.

I've never had a problem with stale fuel myself, but I buy it in 2.5 litre lots I can use up fairly quickly. If it is a problem, there are fuel stabilisers you can buy. They might be a good idea for generators and things that don't get used that much.

 

[R BEADLE]

if its not getting a spark it may have a thin layer of rust built up with standing idle . remove the coil and Emmery ( wet and dry ) the faces that fit above the flywheel . when refitting i use a couple of lengths of insulation tape on the clean fly wheel then fit the coil , the tape will ensure a gap , then turn the fly wheel a little , remove the tape and see what she says regarding a spark . you cant teach an old dog new tricks .

 

[msmbus2000]

Got it sorted today - Not by self tho, had a few other car jobs on so left it into a local guy (old lawnmower repair guy), its running a dream!!! and for the grand some of £15!!! he had one in he was stripping for parts.

All it all its a far better machine now than it ever was, starts on the 2nd pull from stone cold, and 1st when hot.

Thanks for all the replies

 

[Dune]

So what was it?

 

[msmbus2000]

Was a mixture of things:- coil faulty, he changed the fuel and plug and re adjusted the idle speed.

So here's hoping that it sorted for another few yrs yet.