Cold weather-cold starting 550 xp autotune

[brushwacker]

The other day at about 20 degrees after pumping the purge bulb about 6 or 7 times and normal choke procedure I pulled it about a dozen or more times with no pop, so I pumped the bulb 4 or 5 more, tried it them some more. After about 50 pulls i started up my truck and let the saw warm up about an half hour while I cut smallish wood with my old ms180 which started with an extra couple pulls or so which is usually 3 to 6. Both saws were left out in the toolbox in the truck overnight.
Found minimal info searching but the best i could gather, pump the purge 5 times, then choke it normal which is close to what I done but the next cold day I did just that and I believe it was 10 to 12 pulls before it hit. A bit much for a 67 year old man with an somewhat delicate shoulder. I bought this heated handle version so my hands wouldn't ache in cold weather. I have only started and used this saw about 15 tank fulls the few years I had it. Don't remember it starting off cold very well other years either.
So the goal here is will it start and how to start this 550 xp Mk 2 electronic in fewer pulls in 20ish degrees and lower temps without having to bring it inside to warm?
Also does it matter if the heat switch for the handle is on, weaker spark maybe?

 

[FederalQ]

The other day at about 20 degrees after pumping the purge bulb about 6 or 7 times and normal choke procedure I pulled it about a dozen or more times with no pop, so I pumped the bulb 4 or 5 more, tried it them some more. After about 50 pulls i started up my truck and let the saw warm up about an half hour while I cut smallish wood with my old ms180 which started with an extra couple pulls or so which is usually 3 to 6. Both saws were left out in the toolbox in the truck overnight.
Found minimal info searching but the best i could gather, pump the purge 5 times, then choke it normal which is close to what I done but the next cold day I did just that and I believe it was 10 to 12 pulls before it hit. A bit much for a 67 year old man with an somewhat delicate shoulder. I bought this heated handle version so my hands wouldn't ache in cold weather. I have only started and used this saw about 15 tank fulls the few years I had it. Don't remember it starting off cold very well other years either.
So the goal here is will it start and how to start this 550 xp Mk 2 electronic in fewer pulls in 20ish degrees and lower temps without having to bring it inside to warm?
Also does it matter if the heat switch for the handle is on, weaker spark maybe?

I would not believe the heat switch would make a difference to the spark plug, it’s a separate system. I have the same issues with a 550xp, Ms460 arctic, and now Dolmar 7900H when it‘s cold. The Dolmar 6000i will start in 2-3 pulls at -8F however. I wish that saw had heated handles. Warming them up first before heading out is probably the best action.

 

[mainer_in_ak]

It is currently 30 below zero here in interior Alaska and my echo cs 620pw and cs 590 are starting up no problem past few days. The cs 4910 ( 501p with plastic handle) is starting no problem as well. Maybe sell the saw and get something that works with no finnicky bllsht.

 

[Ketchup]

Random ideas:
Does it blow smoke when it finally starts?

How old is your fuel line? I feel like they don’t seal all that well. Could be worse if the line is stiff in the cold.

When you use the primer bulb, does it stay full of fuel?

 

[Stump Shot]

I wouldn't think the heat being on would affect it either, however, I did run across a 550XPG MKII that had that very same affliction. Turn the heat off and vroooom, away it would go.

 

[hacskaroly]

Also does it matter if the heat switch for the handle is on, weaker spark maybe?

Like others have said, I don't think the heat side is stealing any power from the spark. The heated lines are fed by a generator that sits behind the flywheel - totally separate system from the coil/sparkplug. The only thing they share in common is the ground, so if anything it might be the something on the ground side.

 

[Stump Shot]

I think it's just the extra drag on the cold engine that is impeding starting, as the saw needs to hit 800 RPM to generate enough spark to fire. Too slow of a pull can also be a problem as well when it's cold.

 

[EFSM]

I think it's just the extra drag on the cold engine that is impeding starting, as the saw needs to hit 800 RPM to generate enough spark to fire. Too slow of a pull can also be a problem as well when it's cold.

^Sounds logical. A dragging clutch, especially on a concrete saw, can cause the same problem, depending on the ignition timing curve at startup.

 

[legdelimber]

Does the heating element just feed strait from the source coil? When switched on.
How many watts is the heat draw with a cold element?
I could imagine that putting juussssst enough drag to be a factor in a cold weather start.
Typically heating elements have a lower resistance when cold i.e. first put under load.
Inrush current is the term I was taught for it.

Think about pull starting your portable generator with a space heater plugged into and switched on. Not quite as easy as it is with everything unplugged, is it?


Would be interesting to see a heated saw back driven with a small electric motor.
Note the speed of motor and check current drawn by the electric motor.
Then switch on the heating element and look at how much current the electric motor draws when the heating element first puts its load on things.
That surge probably lasts about as long as a saw spins when you pull the starter rope, I'd expect.

edit: or think of starting your push mower in the grass (even already cut) vs rolling it over a bare spot and pulling the rope. I bet some of ya have felt that one over the years.