Shinny 757 Carb help- HDA Walbro

[Jimmy in NC]

Have a 757 that is on the bench right now. Judging the fuel smell it's been sitting for 10 years. Fuel line, filter, kit is in order; given.

I opened up the pump side of the carb and find the pump gaskets stacked like this. Is there any reason for this or was someone just trying to use all the kit parts during a previous repair?

 

[AVB]

Appears to be necessary for the impulse port. It is shown on the IPL for the 757 carburetor. Like you I don't find this setup very often but of course I don't see anything much above 60cc in the line of chainsaws in my small shop.

 

[Jimmy in NC]

Appears to be necessary for the impulse port. It is shown on the IPL for the 757 carburetor. Like you I don't find this setup very often but of course I don't see anything much above 60cc in the line of chainsaws in my small shop.

You were spot on.

Added that extra bit last night and she fired right up. I have never run into impulse running in that way.... but I guess it works.

 

[AVB]

Normally the fuel pump diaphragm will have this area as part of it as I have accidentally install the wrong one a time or two and ended up with fuel running out of the impulse port of the carburetor. This one they must of needed a little extra movement for more fuel flow.