Author Topic: Is there a pulse tube on my chainsaw  (Read 89 times)

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Offline Terry in Almonte

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Is there a pulse tube on my chainsaw
« on: October 07, 2017, 06:57:29 pm »
I have a Canadian Craftsman chainsaw, model 944414430, that I'm trying to get running. It has a Zama C1Q W20 carburetor.

I'm wondering what drives the fuel pump part of the carburetor. I see the fuel line from the fuel filter in the tank to the carburetor, and I see the  two fuel lines from the primer bulb.

But I don't see any line coming from the crankcase or cylinder to the carburetor.

So, what drives the diaphragms in the carburetor?

I also have a Poulan PP3516AVX and I don't see anything like a pulse line on it either.

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Offline Cut4fun .

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Re: Is there a pulse tube on my chainsaw
« Reply #1 on: October 07, 2017, 09:10:14 pm »
Thinking impulse on both of these are from the back of cylinder, through the intake block to the carb.

944414430




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Offline Terry in Almonte

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Re: Is there a pulse tube on my chainsaw
« Reply #2 on: October 22, 2017, 08:18:35 am »
Yes, you're right.

In the bottom image that you provided, with the gaskets and O rings, I can identify the exhaust gasket, the gasket that goes between the cylinder and the intake manifold, and the gasket that goes between the intake manifold and the carburetor.

The pulse comes out of the cylinder through the low hole, next to the lower mounting screw hole. It passes through the low hole in the intake manifold to the carburetor. The carburetor has a semi-circular channel to carry the pulse from the incoming low hole to the top of the carburetor to operate the diaphragm (or flapper valves?) up there.

Not sure where the O rings are intended for, or the two other round things in the bottom image. Can you tell me where these are intended to go?

Thanks

Offline Cut4fun .

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Re: Is there a pulse tube on my chainsaw
« Reply #3 on: October 22, 2017, 09:33:42 am »
I dont recall ever seeing them when I had one torn down.
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Online dpjones

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Re: Is there a pulse tube on my chainsaw
« Reply #4 on: October 22, 2017, 01:04:24 pm »
I think the two big o-rings are for the oil and gas cap.

Offline Terry in Almonte

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Re: Is there a pulse tube on my chainsaw
« Reply #5 on: October 22, 2017, 05:43:00 pm »
That makes sense, big O ring for the gas cap and smaller O ring for the oil cap.
I didn't see the O rings on the caps at first since it was black on black.

Just two more things to identify now. Maybe they're for something on a different saw.

Thanks

 

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