242xp no spark

[Dinosaw]

Long time lurker on here but decided to sign up as I love the Spud/Gardentalk interactions! My 242 stopped suddeny yesterday while sitting on tickover-no spark. plug 2 weeks old and nice and brown. Removed switch and disconnected switch lead from coil, still no spark.Coil gap OK. How do I find out if the coil or blue box is at fault? I have searched all forums and, very surprisingly, have not found an answer.

[spudulike]

Long time lurker on here but decided to sign up as I love the Spud/Gardentalk interactions! My 242 stopped suddeny yesterday while sitting on tickover-no spark. plug 2 weeks old and nice and brown. Removed switch and disconnected switch lead from coil, still no spark.Coil gap OK. How do I find out if the coil or blue box is at fault? I have searched all forums and, very surprisingly, have not found an answer.

 

Nice question, I like that question a lot.....not a clue how to do it though:001_rolleyes:

 

I am guessing measuring the resistance of both units may be a start - I have a 181SE with a similar coil arrangement and can measure the same components. Other than that...not a clue - wet tongue on the plug cap:001_rolleyes:

[Dinosaw]

Thanks for prompt reply Spud. I am not going down the wet tongue road, the dog would be very upset! He only just recovered from the electric fence pee incident! I'll try to measure the coil output with the multimeter but have no figures to compare it to. There's nothing in the service manual. No idea at all how to test blue spark generator, sbstution only, I suppose.

[Dan Forsh]

Without the benefit of clever electrical knowledge, you can get spark testers like Stihl do something called ZAT??? which I think just plugs in line from the ht lead to the plug. There are two versions I think. An expensive one and the older version that costs about £12. I think all these do is give you a visual means of checking for spark production rather than trying to hold the connected spark plug against the cylinder whilst pulling the saw over. Maybe something similar/cheaper from a cars spares place? Maybe try changing the HT lead. These can break down over time. If it's the unit itself, I don't know of anything other than replacing, this is what most of the manuals say anyway.

[GardenKit]

Ah ha, the old 'wet tongue' test. Commonly used by garden shed mechanics:001_tongue:

 

But are you sure there is no spark? I often get customers coming in saying there is no spark and they are often wrong. Sparks seldom fail.

 

How are you testing for a spark?

[Dan Forsh]

Oh yeah, start with easiest first; just because the plug is two weeks old doesn't mean it cannot be the cause of your problem.

[spudulike]

Ah ha, the old 'wet tongue' test. Commonly used by garden shed mechanics:001_tongue:

 

But are you sure there is no spark? I often get customers coming in saying there is no spark and they are often wrong. Sparks seldom fail.

 

How are you testing for a spark?

 

I'll have you know that my workshop is in my garage whilst the wife's car goes green an mouldy in the drive:sneaky2: .....garden shed:001_rolleyes:

 

One thing I have noticed is some saws need a damn hard pull to get a spark - MS660 and MS261 are two I have found - try earthing the plug and giving the pulley a damn hard pull - also try closing the gap up to two A4 paper sheet thicknesses - it may work.

 

The spark testers are a posh way of using a plug with the electrode bent out at 45* from the other central electrode:thumbup:

 

Also check for spark in a dimly lit room - the spark isn't always big blue and fat!

[Dinosaw]

Thanks for all the input. I have used the hold it against the cylinder method and even in the dark there isn't a peep. Bought new plug this morning just in case to try later but I don't think it's the problem. As I said, pity there's no way of checking coil and blue box before replacing.

[elfinwood saws]

Had the same problem a few years a go, cured by fitting another coil, i think a coil off a 181 husky fitted???

[Dinosaw]

Tried new plug, no change. Infinite resistance on coil at rest with only 3 volts output on sharp pull. Think I'll "borrow" the one out of my mate's 254 if it'll fit and see if that works unless anyone has a better suggestion....