MS290 ignition woes

[Butch(OH)]

Have a MS290 on the bench with the following problem. Starts hard and when it starts runs for about 1 second and dies, wont pop again unless you let it sit for 5 minutes then will do same, run for a second then die. Removed kill wire at coil and same problem. Is getting fuel so pulled plug and closed gap to 010 (farmer weak ignition check) and saw starts and runs OK. Installed new plug at correct gap and same problem. Only seems to be two parts to the ignition, the coil and a black box on the back of the jug. Which one or both is problem? and about how much? Thanks in advance.

 

[Peacock]

Sounds like it is probably the coil. I don't really see how the ignition can effect the voltage output of the coil. It is either going to work or not. It simply opens and closes the circuit.

 

[Lakeside53]

The "coil" is actually an electronic trigger and a coil all in one. I don't know of any black box on an 029 that has anything to do with ignition..

Check the gap between the coil and flywheel magnets - should about the same as a business card. If it's correct, your coil is likely bad. The plug gap determines the max voltage the coil can generate. As the gap gets wider, the internal voltage rises and can break down the insulation ("sparks" inside the coil). New - $104. Used - maybe $30-$35... The coil in the 029 is used in many Stihl saws (like 026, 036, 044 etc), so it's easy to find. Part number 0000-400-1300.

Be really careful with the coil screws - very easy to strip out the plastic. If you do, I posted a reliable fix on AS a while back..

 

[Butch(OH)]

The "coil" is actually an electronic trigger and a coil all in one. I don't know of any black box on an 029 that has anything to do with ignition..

Check the gap between the coil and flywheel magnets - should about the same as a business card. If it's correct, your coil is likely bad. The plug gap determines the max voltage the coil can generate. As the gap gets wider, the internal voltage rises and can break down the insulation ("sparks" inside the coil). New - $104. Used - maybe $30-$35... The coil in the 029 is used in many Stihl saws (like 026, 036, 044 etc), so it's easy to find. Part number 0000-400-1300.

Be really careful with the coil screws - very easy to strip out the plastic. If you do, I posted a reliable fix on AS a while back..

Thanks Andy, What I am calling a "black box" if you have the starter and cover off, is attached (I think) to the motor block to the left of the coil and behind the flywheel and has two wires between it and the coil. Can get picture if that helps.

 

[Lakeside53]

That's just the grounding wires to the coil.. Oh yes, make sure they are intact!