Hello this is my first post. My MS 310 has a wiring issue that I can’t fix. I have tried to find a schematic detailing the simple wire harness with little luck. Any chance one of you could explain the wiring layout. The wire going to the ground point on the coil broke off so I ran another wire from it to the metal dogs up front. I would like to trace the wire but I believe I would need to dismantle the entire saw ? Any suggestions would be appreciated.
MS 310 Coil Wiring Help ?
- Thread starter jpsbgt
- Start date
Photos will help- but the ground is a T27 screw located on the flywheel side of the cylinder- just to the front of and slightly above the coil- should be a wire with a ring terminal from the coil and another going away to the metal section of the master control switch.
Well you have to pull the recoil starter off and enough of the saw to expose the flywheel- but should be plain to see after that.
The cover is off ! No visible sign of ground wire. Just the two yellow wires going into a plastic access area. You can not see the area on cylinder where the wire terminates inside. I have spark but saw will not run. I shot a bit of starting fluid but nothing ?
If you have to resort to starter fluid- you have bigger issues.
Okay- Stihl plastic case consumer grade saws are all pretty much the same- one wire with a ring terminal runs alongside the sparkplug wire and has a spade female terminal that goes onto the flat bit of spring steel that acts as the kill switch on the master control- also a black wire- spade female at coil end, copper tube at other- this is what the spring flat steel contacts at the master control switch to ground the coil.
There should be a short jumper wire with two ring terminals that go at coil mounting bolt to a bolt on the cylinder so the coil can be grounded- as otherwise it is mounted to insulated plastic and the stop/kill switch will never work.
Okay- Stihl plastic case consumer grade saws are all pretty much the same- one wire with a ring terminal runs alongside the sparkplug wire and has a spade female terminal that goes onto the flat bit of spring steel that acts as the kill switch on the master control- also a black wire- spade female at coil end, copper tube at other- this is what the spring flat steel contacts at the master control switch to ground the coil.
There should be a short jumper wire with two ring terminals that go at coil mounting bolt to a bolt on the cylinder so the coil can be grounded- as otherwise it is mounted to insulated plastic and the stop/kill switch will never work.
I have always been told that if you have spark , fuel and compression the engine should run. I tried the starting fluid just to eliminate lack of fuel as a reason it won’t run. I am assuming that the one yellow wire going to the cylinder ground point has come off or broke off from vibration. I confirmed spark by holding the plug against the cylinder head, strong spark. Engine has great compression ! Very confusing ! Bob I see no short jumper wire you mentioned ? I will open up the cover again and take a photo. Really appreciate your time and patience.
Spark, fuel and compression is a general minimum and assumes a few things.
You also need correct timing of that spark and the correct air/fuel mixture reaching the combustion chamber.
So a shorn key on the flywheel, or substantial air leak can stop a saw from firing.
Compression- unless measured with a true small engine gauge- is subjective also.
As a rule, I am not fond of the big Stihl plastic saws- have lots of non repairable wrecks here to prove it- but with any saw, it comes down to the same basics and a pressure and vacuum test will eliminate a LOT of guessing and parts chucking.
You also need correct timing of that spark and the correct air/fuel mixture reaching the combustion chamber.
So a shorn key on the flywheel, or substantial air leak can stop a saw from firing.
Compression- unless measured with a true small engine gauge- is subjective also.
As a rule, I am not fond of the big Stihl plastic saws- have lots of non repairable wrecks here to prove it- but with any saw, it comes down to the same basics and a pressure and vacuum test will eliminate a LOT of guessing and parts chucking.
Well stated Bob ! Saw operated perfect last November. Went to start it in April and nothing. Borrowed a friend’s to clean up from a windstorm and just now getting back to figuring out the issue. I always run the saw out of gas before I put it away. Fresh non-ethanol with Royal Purple two stroke oil. New air filter. Going out to take a photo of the coil and wiring.
Bob I have determined that you need to pull off the flywheel to inspect the ground wire on the cylinder, I believe I can see it but not certain that the wire is connected properly with no short or broken. I can’t do it until tomorrow.