trimmer MCCULLOCH coil assembly testing

A

angellonewolf

Well-Known Member
i have MCCULLOCH trimmer non starting

i put in a new spark plug still no spark

i have cheaked the kill switch makes and brakes the earth to stop the engine

i assume this is a electronic coil as there are no points or condenser
 

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If you have cranked it with a known good plug, with the wires unplugged from the module, then you have basically tested the coil and found it is faulty.
 
A quick test with the multimeter will show if there is continuity between the low tension terminal (which is used to switch off the engine) and earth.
if so, Oh dear, time for a new part.
 
EngineMan said:
A quick test with the multimeter will show if there is continuity between the low tension terminal (which is used to switch off the engine) and earth.
if so, Oh dear, time for a new part.
Click to expand...

can you show me on a pic please ?
where to put the test meter thanks angel
 
low tension terminal (top), (which is used to switch off the engine) and the earth terminal (bottom) the one that comes back from the switch.
 

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Have you checked the air gap. set it around .010 (.25mm)

Disconnect both wires (small one's) on the coil, and see if you have a spark.

If you have, check the wires for a short to ground.

Also check the kill switch.

If there is no spark, hold a screwdriver against the magnets on the flywheel to feel if they are magnetic.

If the are good, replace the module. If not replace the flywheel.

Remember.....A coil can fool you also they short inside and measure fine but wont spark.
 
thanks for all the help engine man ITS ALIVE

well no realy but i do not know what the problem was but after taking apart all of the wires and just looking for spark then it sparks
so i then put back the stop wires in still sparks then put back on the stop switch it still sparks so i do not know what was stopping it sparking but after taking apart and putting back together in stages there is a spark

sorry to say i cant fully test it as the fuel lines need replacing as one of them are split and all are old and brittle so will have to get some more before trying but now i have got compression and spark and very hopeful now i got 95 % of it now working and know it worth spending a few quid on the pipes and bits

will post back later in the week to say how it got on thanks for all the help guys
 
Angell, A while back I found the US patent on line for a solid state coil with no moving parts (1970). A couple of us were wondering about ignition advance , if any, Anyway that coil is about 2 inches long and has two "shoes." It was designed for chain saw application. Why am I telling you this? Unlike the primitive 4 strokers which seem happy to fire before or after TDC and run at 3000, the little 2 strokes want (apparently ) 22 degrees of full advance and get it from this coil (for 7000 rpm). I notice a big adjustment slot showing on your pic. Have you set it to the factory setting? I don't know what it is and IL ENG may be right at .010 air gap . Also note which "shoe" you are setting. Could you have the wrong starting ignition setting? Only an idea.
 
sorry for not getting back to you have been lerking around but moved house a year ago and now in the last few months some of the big jobs round the house have been done so i have a lot of jobs to do around the hose bathroom kitchen landscape garden

on doing the garden i removed the need for the trimmer and sold it to a mate its stll going as fair as i know
 
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