Chainsaw won't re-start when Hot

[Iplayfarmer]

I've got a cheapo poulan chainsaw that I bought a few years ago for $5 at a yard sale. It's worked great for what I've used it for. I mostly just use it to trim small branches and occasionally cut a bit of firewood for camping.

The problem with it is that if I shut it of after it's warmed up, I can't get it to start again until it's cooled down.

Any ideas?

 

[amaxwell]

Check the screws holding the carb. to the engine ,mine had gotten loose and was letting too much air in causing hard starting when warm.
Amaxwell

 

[bstillw]

I had a Poulan that did the same thing. I usually clean my saws with the water hose. Did it one day when it wouldn't start and gave it a pull and it cranked right up. So after that, when it wouldn't restart, I would just hose it down under a water faucet and fire it back up. Didn't try it, but if you are out in the woods a jug of water might accomplish the same thing. Do avoid spraying a lot of water in the exhaust, otherwise just douse it good. Don't know if it was vapor lock or what but I didn't worry about what it was anymore!

 

[arrow]

It is getting hot for one of 4 reasons. !. Change out the spark plug and clean the fuel filter. It may be running so lean because of insufficent fuel supply, that the ignition module heats up and will not start the saw until it cools down 2. The plug is bad enough so it will not send sufficient spark until it cools down. 3. The ignition module is on the way out (I've seen ignition modules mostly just fail. There was one guy I worked with though whose saw was doing something similar to yours and his shop said it was the ignition module) 4. You are getting vapor locked.

 

[Iplayfarmer]

It is getting hot for one of 4 reasons. !. Change out the spark plug and clean the fuel filter. It may be running so lean because of insufficent fuel supply, that the ignition module heats up and will not start the saw until it cools down 2. The plug is bad enough so it will not send sufficient spark until it cools down. 3. The ignition module is on the way out (I've seen ignition modules mostly just fail. There was one guy I worked with though whose saw was doing something similar to yours and his shop said it was the ignition module) 4. You are getting vapor locked.

It must be #4 because when I spray carb cleaner down the intake it fires right up and runs for a few seconds. I've definately got spark.

 

[arrow]

You can have sufficient spark enough to start it but if the plug has reached its end, it will not keep the saw running as the insides heat up sufficiently enough to shut down current transfer. Clean out the fuel filter, replace the plug, For 2 bucks, you may not have to put up with this at all.

 

[ray66v]

It must be #4 because when I spray carb cleaner down the intake it fires right up and runs for a few seconds. I've definately got spark.

A lot of people have posted on the internet about vapor lock issues with the fine federal government subsidized fuels we now have.

Additionally, fuel lines and filters are often being eaten up particularly in garden equipment, sometimes causing restricted flow, aggravating the problem.

I recommend Replacing the fuel line, and filter. Look for the possibility of rerouting the line where its not as hot, (very little chance in a chain saw). And, if necessary, experiment with simple heat shields like aluminum foil, wrapped around the fuel tank, the carb, and fuel line.

 

[Tig]

I also agree on the fuel filter / vapour lock. My father's McCulloch does the same thing.

 

[Dmace]

Typically when a chainsaw wont start when warmed but starts and runs fine when cool, it's because the air/fuel ratio is too rich (too much fuel). It starts fine when cold because extra fuel is the same as using a choke. When it's warm and still too much fuel, it's flooding. Can you start a warm engine with the choke wide open... Nope.

Let it cool down and then start it, screw in the air/fuel mixture screw about 1/4 turn at a time and give her a few wide open runs between each turn until it sounds raspy or shows little to no smoke. When it does, turn it out 1/4 turn and try that out. After some use, keep an eye on the spark plug and if it looks white then you are too lean (too much air) and if it is back then you are too rich (too much fuel). You are looking for a nice light brown. For cheap saws, Poulan makes a good starter.

 

[RWEST]

I bought a few years ago for $5 at a yard sale

For 2 bucks, you may not have to put up with this at all.

But that's 40% of what he paid for it!!
Sorry - couldn't help it.

These are all good suggestions, BTW.

 

[Iplayfarmer]

But that's 40% of what he paid for it!!
Sorry - couldn't help it.

These are all good suggestions, BTW.

I actually bought a new spark plug and a new fuel filter the day I bought the saw. That was about two years ago. It may be the spark plug, but this saw has never run perfect.

I was just thinking about this thread yesterday. I need to get back out and try some of the suggestions to fix the saw, but I've been distracted with some other projects. Plus it's been raining here for a week straight. That kind of takes the ambition out of me when I don't have a heated shop.

 

[Tig]

I've got my dad's saw apart in the garage right now. After seeing how it it assembled I am a bit skeptical that vapour lock is the issue here. I will try to protect the fuel line and also check the carb settings.
There is nothing worse than an unreliable tool.

 

[Iplayfarmer]

I've got my dad's saw apart in the garage right now. After seeing how it it assembled I am a bit skeptical that vapour lock is the issue here. I will try to protect the fuel line and also check the carb settings.
There is nothing worse than an unreliable tool.

How likely is it to be carb settings? Could it just be a mixture screw setting or something?

 

[6string]

If it's yellow,give it to another fellow!

 

[Iplayfarmer]

If it's yellow,give it to another fellow!

It's kind of a greenish yellow. Does that count?

The thing is, I don't need a chainsaw enough to go out and replace this one. If I don't get this one fixed, I'll just do without. But, it's nice to have around.

 

[ToadHill]

I had the same problem on my saw and found that the fuel line had some pin holes in it and I guess when it heated up, it didn't deliver enough fuel to the carb.

 

[Iplayfarmer]

I had the same problem on my saw and found that the fuel line had some pin holes in it and I guess when it heated up, it didn't deliver enough fuel to the carb.

I wonder if that's it. When it pulls the "won't start when hot" attitude with me, I can sometimes get it going by priming it a little with carb cleaner. It would make sense if there's a pin hole in the line that it would not prime the line at hand-pulling speeds, but that could be overcome at engine speed.

How much could a fuel line cost? It's got to be worth a try.

 

[Tig]

Well I'm done and three things came to my attention.
One, working on a McCulloch MacCat is like peeling an onion.
Two, the intake manifold was not installed properly The clamp that seals it to the cylinder head flange was doing nothing. Possible air leak there. Looks like it was like that for a long time.
Three, the air filter was over oiled. I'm surprised it ran as well as it did.
After I took care of the last two two details, it ran fine and started when hot. Carb adjustment was close as it was. Go figure, Dad always seems to tune things a bit rich in my opinion.
My dad is real proud of his chainsaw, it drives me crazy. Dad's gone till spring so I'll see if I can make peace with this machine. It still needs a fuel filter and a new spark plug wouldn't hurt either. Although changing the plug means peeling the onion again.

 

[bontai_Joe]

Sounds to me like it ran great as was for being a $5 saw, I'm lazy enough to have just lived with it that way, but I agree that it's nice to get it running better for minimal money.

 

[Iplayfarmer]

It's done what I need it to do so far. It's just kind of a personal quest now. If it's a cheap and simple fix to get it running right it would sure be nice to have a dependable saw even if it's not a super big or powerful saw.