ms 661 no spark

[rupedoggy]

Rebuilt a 661c that had the piston in backwards. It ran for a long time but the ring eventually caught on the exhaust port and broke off a piece of ring. Cylinder OK so a new piston and clean up on cylinder. Has great compression now but no spark! Traced down all the wires, reset gap. Still no spark. Took off plug in to the coil (Wirers from the carb box) and spun with my drill still nada. This is the A coil. Is this an EPA emission guarantee thing? Any ideas??????????

 

[adam32]

Something simple like the switch grounding out? Did you try a new plug?

 

[singinwoodwackr]

Rebuilt a 661c that had the piston in backwards. It ran for a long time but the ring eventually caught on the exhaust port and broke off a piece of ring. Cylinder OK so a new piston and clean up on cylinder. Has great compression now but no spark! Traced down all the wires, reset gap. Still no spark. Took off plug in to the coil (Wirers from the carb box) and spun with my drill still nada. This is the A coil. Is this an EPA emission guarantee thing? Any ideas??????????

Run the wiring harness for tone…all wires

 

[rupedoggy]

Great ideas for sure. I have indeed changed plugs and traced down the wiring. When I disconnect the wires to the coil shouldn't I get a spark if the coil is good?

 

[singinwoodwackr]

Great ideas for sure. I have indeed changed plugs and traced down the wiring. When I disconnect the wires to the coil shouldn't I get a spark if the coil is good?

It is difficult to get a good spark test on mtronics

 

[SteveSr]

Great ideas for sure. I have indeed changed plugs and traced down the wiring. When I disconnect the wires to the coil shouldn't I get a spark if the coil is good?

Assuming that this saw is M-Tronic... A wiring harness problem will kill the spark. The computer runs a diagnostic on the wiring harness and if it doesn't like what is finds it kills the ignition. You also need sufficient cranking speed which you may not get from your drill.

 

[rupedoggy]

The saw is indeed m-tronic. However without the wires hooked to the coil it should not be able to kill spark. Does it need the wires hooked up to provide spark? All the saws I have ever tested showed spark with this drill motor speed. Mike

 

[SteveSr]

The saw is indeed m-tronic. However without the wires hooked to the coil it should not be able to kill spark. Does it need the wires hooked up to provide spark?

M-Tronic is a completely different animal from a conventional coil. If it can't sense a connected solenoid (due to a wiring harness issue) it can't control the engine and therefore no spark.

It may also check for the functionality of the on/off/start switch as well. I don't know if the switch can be disconnected from the harness or not. If it can, once you get it running, you can try this as well to see if it will run with the switch disconnected.

All the saws I have ever tested showed spark with this drill motor speed. Mike

The M-Tronic processor requires more power which is one reason that there are twice as many magnets on the FW. Even with this cranking speed may be a factor. Another thing to test once you get it running.

 

[rupedoggy]

It used to be easy and I didn't know it!

 

[glock37]

everything in saw needs hooked up to work
make sure if the connector on coil has a screw make sure its tight
take plug out and turn saw over with a drill on flywheel side counterclockwise

 

[rupedoggy]

OK good to know. The coil is held on with two screws the same as most but the wires are in a rubberized fitting that snaps onto the side of the coil. Mike