chainsaw won't start and I'm running out of ideas

[jklier]

I've got a Poulan Woodshark S1970. It's an older saw but not many hours on it. I used it with no issues several weeks ago. The following week it would no longer start. It won't even attempt to start, like the spark plus is unplugged.
Here's what I've done so far.

1. pulled the plug to check for spark. The original plug was a little dirty so I put in a new one. New plug shows a nice blue spark. Nothing. I tried a second new plug. Got spark but no ignition.
2. Checked fuel. New plug smelled of fuel when I pulled it back out so I assumed it was fine. Just in case it was flooding. I let it sit for a day with the plug out. I primed it with a little gas in the plug hole and tired again. Nothing.
3. Installed another brand new carburetor. Changed all of the fuel lines and filter. Nothing.
4. Checked compression. 150psi
5. Made sure airgap at coil was 0.35

So what's next? Is it possible a still have a bad coil that's not firing under compression? I suppose I could check resistance on the primary and secondary but I don't know what the specs for this coil are. Anyone of any other ideas?

Thanks - John

 

[WBarnett]

Have you checked both wires that run to your on off switch?

 

[Madmantrapper]

.35 coil gap is excessive even if you meant to say .035. Should be more like .010.

 

[jklier]

Yes, I checked them when I was checking the airgap on the coil. I pulled them out of the sleeve to make sure the insulation wasn't broken anywhere and checked them for continuity.

I also checked that the spark arrestor was clean which I forgot to mention.

 

[jklier]

.35 coil gap is excessive even if you meant to say .035. Should be more like .010.

0.35mm which is about 0.014. Sorry, that was my fault for not stating units.

 

[Bobby Kirbos]

Have you checked both wires that run to your on off switch?

• I assume the coil is gapped at 0.035", not 0.35"... big difference like 5/16" of a difference
  That gap seems excessive. Most coils gap at around 0.012" (the thickness of a business card).
• Have you checked the switch itself to make sure that it is opening and closing correctly?
• Have you checked to make sure that the switch hasn't found a way to physically rotate in its hole - as in, you think the saw should be "ON" when in fact it's actually in the "OFF" position.
• Is this a reed engine? Could a reed be jammed open?

 

[WBarnett]

I've got a 3314 thats missing bar and chain wrap handle and top cover that you can have for parts if you want it. I'm located in oklahoma

 

[jklier]

• I assume the coil is gapped at 0.035", not 0.35"... big difference like 5/16" of a difference
  That gap seems excessive. Most coils gap at around 0.012" (the thickness of a business card).
• Have you checked the switch itself to make sure that it is opening and closing correctly?
• Have you checked to make sure that the switch hasn't found a way to physically rotate in its hole - as in, you think the saw should be "ON" when in fact it's actually in the "OFF" position.
• Is this a reed engine? Could a reed be jammed open?

I was working in mm, sorry for not stating units. Gap is 0.35 mm or about 0.014. I tried starting with the switch unplugged. I assume that should have eliminated the switch as an issue. I'm not familiar with what a reed engine is.

 

[Old2stroke]

Even if the reeds are bad, with that kind of compression and a good spark, it should show some sign of life if you drool some fuel in the spark plug hole. Timing could be wrong so you have to pull the flywheel and make sure the key hasn't been sheared and the FW shifted. I believe that saw has a points ignition, so also check for correct points gap. If it's too far off, the timing will be too. To check for ignition strength, see if it will fire a plug gapped to about 0.080". If it will fire this in air it should also fire a plug with the right gap in the engine.

 

[RED-85-Z51]

S1970 should be a stratocharged model about 10 years old.

Sent from my LM-G820 using Tapatalk

 

[rupedoggy]

I think it's flooded

 

[TrashCutter]

. If it's too far off, the timing will be too. To check for ignition strength, see if it will fire a plug gapped to about 0.080". If it will fire this in air it should also fire a plug with the right gap in the engine.

Thanks for that advice, have always wondered if there was a "seat of the pants" way to see if the high tension system was adequate, although would have thought the minimum distance for the spark to jump would be much bigger than 0.08"

Suppose it could vary with elevation and humidity too?

 

[lone wolf]

I've got a Poulan Woodshark S1970. It's an older saw but not many hours on it. I used it with no issues several weeks ago. The following week it would no longer start. It won't even attempt to start, like the spark plus is unplugged.
Here's what I've done so far.

1. pulled the plug to check for spark. The original plug was a little dirty so I put in a new one. New plug shows a nice blue spark. Nothing. I tried a second new plug. Got spark but no ignition.
2. Checked fuel. New plug smelled of fuel when I pulled it back out so I assumed it was fine. Just in case it was flooding. I let it sit for a day with the plug out. I primed it with a little gas in the plug hole and tired again. Nothing.
3. Installed another brand new carburetor. Changed all of the fuel lines and filter. Nothing.
4. Checked compression. 150psi
5. Made sure airgap at coil was 0.35

So what's next? Is it possible a still have a bad coil that's not firing under compression? I suppose I could check resistance on the primary and secondary but I don't know what the specs for this coil are. Anyone of any other ideas?

Thanks - John

How about trying some new fresh mixed gas in it?

 

[jklier]

How about trying some new fresh mixed gas in it?

Tank was completely drained when I changed the lines and put on the new carb. Gas was a fresh as it could possibly be.

 

[jklier]

I think it's flooded

Even after sitting all night with the plug out?

 

[jklier]

Even if the reeds are bad, with that kind of compression and a good spark, it should show some sign of life if you drool some fuel in the spark plug hole. Timing could be wrong so you have to pull the flywheel and make sure the key hasn't been sheared and the FW shifted. I believe that saw has a points ignition, so also check for correct points gap. If it's too far off, the timing will be too. To check for ignition strength, see if it will fire a plug gapped to about 0.080". If it will fire this in air it should also fire a plug with the right gap in the engine.

I'll pull the flywheel tomorrow and check.

Do you think it would be worth checking resistance on the coil?

 

[lone wolf]

I've got a Poulan Woodshark S1970. It's an older saw but not many hours on it. I used it with no issues several weeks ago. The following week it would no longer start. It won't even attempt to start, like the spark plus is unplugged.
Here's what I've done so far.

1. pulled the plug to check for spark. The original plug was a little dirty so I put in a new one. New plug shows a nice blue spark. Nothing. I tried a second new plug. Got spark but no ignition.
2. Checked fuel. New plug smelled of fuel when I pulled it back out so I assumed it was fine. Just in case it was flooding. I let it sit for a day with the plug out. I primed it with a little gas in the plug hole and tired again. Nothing.
3. Installed another brand new carburetor. Changed all of the fuel lines and filter. Nothing.
4. Checked compression. 150psi
5. Made sure airgap at coil was 0.35

So what's next? Is it possible a still have a bad coil that's not firing under compression? I suppose I could check resistance on the primary and secondary but I don't know what the specs for this coil are. Anyone of any other ideas?

Thanks - John

Another brand of carb jumps at me! Will it momentarily fire if you put a small amount of fuel in the carb throat?

 

[jklier]

Another brand of carb jumps at me! Will it momentarily fire if you put a small amount of fuel in the carb throat?

No, it won't. I let it dry out all night with the plug out. The next morning I put a small amount of fuel in the hole, plugged it up, and gave it a pull. Absolutely nothing. This was with a new plug, new fuel lines and filter, and a new carb. The only thing left that I can think of is the coil.

 

[lone wolf]

No, it won't. I let it dry out all night with the plug out. The next morning I put a small amount of fuel in the hole, plugged it up, and gave it a pull. Absolutely nothing. This was with a new plug, new fuel lines and filter, and a new carb. The only thing left that I can think of is the coil.

You checked the flywheel key I guess right? Could be the coil or the flywheel maybe. Pull the muffler and look at the piston while you are at it.

 

[MacAttack]

One other thing to try...like Rupedoggy said, it could be severely flooded, crankcase full of gas. Flip it upside down with the plug out, and pull it over like crazy and see if fuel spatters out. If so, keep pulling until you see nothing more than a slight mist. I have had things do what you described, and I had to do that to clear them out, even after sitting.