MS261C will not start

[PhillH]

10 minutes ago, ChrisNewport said:

Does it spark with the original coil on but not fire with fluid in the plug hole? Scoring to the piston isnt always on the exhaust side. Id pull the cylinder.

Both coils are sparking, I do not think there is actually anything wrong with the original coil other then my dad not pulling it over hard enough because when I swapped them i didn’t think the new coil was sparking but after reading a few post people said pull them over quicker which I did and got a spark. 
 

swapping the coils makes no difference, fuel in the bore or through the carb air intake makes no difference. Choke on or wide open throttle makes no difference 

 

I smoke from the exhaust with a wide open throttle but it does not pop what so ever 

 

cheers

[adw]

Stop messing about with it, just lift the cylinder and check the condition of the piston.

[PhillH]

18 minutes ago, adw said:

Stop messing about with it, just lift the cylinder and check the condition of the piston.

I will do as soon as I can, Christmas has got in the way of tinkering time  

[PhillH]

Hi all,

saw is now running. I checked the compression tester on a running saw of similar size. That also had a reading of 125psi so I was reluctant to remove the cylinder. I removed the carb and checked the boot, I could see the inlet side of the piston and it was ok.

I checked continuity on the wiring harness and found no issues. 

 

After a lot of research on google I found a post from someone stating that the coil will cut the spark if it detects a faulty solenoid so I thought for £20 it was worth a try. 

 

Purchased a white solenoid and fuel filter and saw started straight away. 

 

It is very strange that there was a spark every time when pulling the saw over with the plug out but it does explain the change in note when trying to start the saw, one second it sounds like it’s about to fire then it sounded different as though there was nothing at all.

 

Anyway it’s a mystery solved, thanks to everyone for there help and I hope my update may help someone else. 

[Stubby]

22 hours ago, PhillH said:

 

Hi all,

saw is now running. I checked the compression tester on a running saw of similar size. That also had a reading of 125psi so I was reluctant to remove the cylinder. I removed the carb and checked the boot, I could see the inlet side of the piston and it was ok.

I checked continuity on the wiring harness and found no issues. 

 

After a lot of research on google I found a post from someone stating that the coil will cut the spark if it detects a faulty solenoid so I thought for £20 it was worth a try. 

 

Purchased a white solenoid and fuel filter and saw started straight away. 

 

It is very strange that there was a spark every time when pulling the saw over with the plug out but it does explain the change in note when trying to start the saw, one second it sounds like it’s about to fire then it sounded different as though there was nothing at all.

 

Anyway it’s a mystery solved, thanks to everyone for there help and I hope my update may help someone else. 

Thanks for getting back and I am glad its now running . I still think 125psi is on the low side but maybe due to the type of compression tester you have used .

[spudulike]

Good news, faulty solenoids usually just cause stalling on idle but you live and learn, all good in the end.

[Dan Maynard]

Maybe that spark cutout has saved you running lean with a faulty solenoid, so a good safety feature?

[PhillH]

On 05/01/2025 at 18:13, Stubby said:

Thanks for getting back and I am glad its now running . I still think 125psi is on the low side but maybe due to the type of compression tester you have used .

Hi @Stubby I think it will be my compression tester as it certainly feels like it has good compression. My arm was hanging off from pulling it over. Thanks again

[PhillH]

On 05/01/2025 at 19:19, spudulike said:

Good news, faulty solenoids usually just cause stalling on idle but you live and learn, all good in the end.

Hi @spudulike exactly, it was misleading hence why I never changed the fuel solenoid at the beginning. Thanks again

[PhillH]

On 05/01/2025 at 20:18, Dan Maynard said:

Maybe that spark cutout has saved you running lean with a faulty solenoid, so a good safety feature?

Hi @Dan Maynard yes possibly, it was strange that the plug was sparking when not fitted. Would have expected to see it cut the spark even when ground.