Husqvarna Partner K960 Rescue Saw Problem

[501Maico]

Hello all,
I was asked to look at this saw that won't rev past idle. The firing at idle is consistent but it doesn't seem like there are enough of them. I count about 4 fires per second from the muffler outlet and see the same number with a neon test light on the ignition wire. Ignition problem?

 

[Chevboy0167]

Air filter clean? Air intake in front of and behind the carb clear? Muffler and or screen plugged up with carbon? Exhaust port on cylinder clear?

Sounds like it may be starving for air movement.... These and concrete saws take a beating and can plug up often if they get used a lot without regular maintenance. I went through 2 Stihl TS420 concrete saws last summer that were very plugged up to the point that they barley ran.

Fuel filters, fuel pump gaskets and metering diaphragms in the carb can get weak to the point of not working.

Start with a compression test to see if the cylinder is healthy enough to justify digging in deeper..... These can be a deep and filthy rabbit hole.

 

[501Maico]

Air filter clean? Air intake in front of and behind the carb clear? Muffler and or screen plugged up with carbon? Exhaust port on cylinder clear?

Sounds like it may be starving for air movement.... These and concrete saws take a beating and can plug up often if they get used a lot without regular maintenance. I went through 2 Stihl TS420 concrete saws last summer that were very plugged up to the point that they barley ran.

Fuel filters, fuel pump gaskets and metering diaphragms in the carb can get weak to the point of not working.

Start with a compression test to see if the cylinder is healthy enough to justify digging in deeper..... These can be a deep and filthy rabbit hole.

Air filters are clean and removed while testing. I asked the first guy that worked on the saw to check the muffler/port and he said it was clean. Exhaust is forceful every time it fires.

We mainly use these saws for metal and it's very clean. Probably never seen concrete. Saw has a nice throaty sound at the carb intake when throttle is opened, but the saw doesn't speed up much. A small squirt of starting fluid starts to kill the saw.

I gathered some more information since my first post. The saw is running 2500 rpm at idle measured with a mechanical tach. I counted 25 fires in 5 seconds, so around 300 sparks per minute. I'll check the flywheel magnets for metal and the air gap. If OK I guess it has to be the coil.

 

[501Maico]

New coil took care of the problem.