Poulan P1970 stopped and won't fire back up

[jklier]

I ran this saw for about an hour when it suddenly stopped. I could not get it to fire back up. I had a spare (new) carb and new plug so I put those on, no change. When I pulled the fuel line coming from the tank it squirted fuel so the tank appears to have pressure. I'm using a fresh can of the pre mixed fuel so bad fuel shouldn't be the issue. I pulled the plug and let the cylinder dry out then tried using a shot of starter fluid, nothing. Compression is good 120+. Muffler is not clogged. Reset the gap on the ignition module, no change. I tried 3 spark plugs, all showed spark when pulled off engine.

What have I missed? Is there a chance the spark is too weak? The arcs looked blue.

Appreciate any advice.

 

[coffeebrk]

Pull muffler and look at the piston and report back

 

[jklier]

Pull muffler and look at the piston and report back

Also, I went back and checked compression again. It's just a hair over 140.

 

[coffeebrk]

Looking scored to me

 

[jklier]

Wouldn't that affect compression? Not arguing, just educating myself.

 

[coffeebrk]

Yes and no. I always pull muffler when buying a used saw. Compression test, either gauge or by stater rope may not indicate a scored piston 100% of the time

 

[jklier]

Again, just for my own education, how would a moderately scored piston cause a no fire scenario if all of the other boxes are checked? If this is the cause of my issue then I'm assuming it's likely not worth fixing. I think I paid $120 new for this one 20+ years ago. A new 14" saw at Home Depot is $149. Really appreciate you sharing your knowledge.

 

[coffeebrk]

You've stated 2 different compression numbers already. Unless you have a very accurate Guage for small engines that likely will be the answer

 

[jklier]

When I ran it the first time I saw it hit over 120 then I stopped. I was incorrectly thinking that 120 was adequate. My mistake. When you mentioned the scored piston I decided to go back and check it properly.

 

[jklier]

This is what I'm using to check compression.

 

[rupedoggy]

Maybe I am wrong, and I hope I am< but it does not look like there are any rings on that piston.

 

[jklier]

Maybe I am wrong, and I hope I am< but it does not look like there are any rings on that piston.

It is getting compression somehow. A bit over 140 when I checked it properly the second time.

 

[Okie]

I tried to look at a parts list for your P1970

Appears to be a Strato type (additional butterfly above the carb intake.
First install a new correct gapped proper shark plug.
if the following looks normal.
The little boot hose between the Strato input and the manifold has to be sealed good, no air leaks.
Next some of them Poulan carbs have a black plastic lever on the strato shaft and a spring to hold the strato butterfly closed WHREN NOT At FULL THROTTLE. Other types of carbs have a metal rod linkage and not as likely to break but require cutting away some of the edge of the rubber intake on the side to go to this type so the linkage does not rub on the side of the intake seal.
If any air leaks in this area or the strato is slightly open she won't start and usually not even promise to pop.
If the strato butterfly is not spring loaded closed, fix it closed and start the saw and it should idle. If the little hose is split remove it and tape the cracks and test,

Summary: all of the strato input has to be sealed good for a low and mid rpm start/run.

 

[coffeebrk]

It is getting compression somehow. A bit over 140 when I checked it properly the second time.

That's when the saw is cold.

 

[jklier]

Maybe I am wrong, and I hope I am< but it does not look like there are any rings on that piston.

Well, looks like you are right. I pulled the muffler back off and confirmed that both rings are gone. Guess I'll be replacing it after all. Thanks for pointing that out.

 

[jklier]

That's when the saw is cold.

Yep, you are correct. Looks like the cool oil/fuel was enough to get some compression. There are no rings on the piston. Thanks again for your replies.

 

[Okie]

Yep, you are correct. Looks like the cool oil/fuel was enough to get some compression. There are no rings on the piston. Thanks again for your replies.

WOW:
Them rings evaporated.
Consumable rings. Not a surprise to me it being a Poulan.
In same category as consumable stitches.

I'm thinking it probably came from the factory as such.

Poulans/Crapsmans are really good for getting chainsaw experience's.