B&D 675E Govenor Spring Assembly

[barberino]

Hey guys.

I am currently troubleshooting a swisher string trimmer that is barely firing and then immediately dieing.

It has an auto-choke system that I'm not familiar with. There is no manual choke on the machine, just a primer.

I'm wondering if it is missing a spring. I tried looking at the parts diagrams but could not make sense of it because the parts diagrams included multiple diagrams for multiple variations of the same engine but did a poor job specifying which diagram went with which engine.

I've included a picture. The other reason I'm wondering if this system is working is because the choke is always open, I figured it should start close then open as it runs. There is no muffler bi-metal spring that I can see. Even a quick run-down on how auto-choke works could help me a lot.

I have cleaned the carburetor, checked for spark, replaced fresh gas...I will confess the only thing I haven't done is check that the gas cap vent is working properly, but wanted to get this posting out there because regardless I am really curious as to how that auto-choke works.

Thanks, hope that provides all the info ya fellow gear-heads need. If not I'll reply shortly, and as always hopefully someone else will learn from my experience.

Mod: 126M02-0444-F1

If this isn't the case, I'm going to proceed with a carburetor rebuild.

 

[Ifixdit]

Hey guys.

I am currently troubleshooting a swisher string trimmer that is barely firing and then immediately dieing.

It has an auto-choke system that I'm not familiar with. There is no manual choke on the machine, just a primer.

I'm wondering if it is missing a spring. I tried looking at the parts diagrams but could not make sense of it because the parts diagrams included multiple diagrams for multiple variations of the same engine but did a poor job specifying which diagram went with which engine.

I've included a picture. The other reason I'm wondering if this system is working is because the choke is always open, I figured it should start close then open as it runs. There is no muffler bi-metal spring that I can see. Even a quick run-down on how auto-choke works could help me a lot.

I have cleaned the carburetor, checked for spark, replaced fresh gas...I will confess the only thing I haven't done is check that the gas cap vent is working properly, but wanted to get this posting out there because regardless I am really curious as to how that auto-choke works.

Thanks, hope that provides all the info ya fellow gear-heads need. If not I'll reply shortly, and as always hopefully someone else will learn from my experience.

Mod: 126M02-0444-F1

If this isn't the case, I'm going to proceed with a carburetor rebuild.

View attachment 15118

There is not an auto-choke mechanism on the carb in the picture you provided. If so there would be a plastic arm held on by a 1/4" head screw that mounts to the top of the carb. The auto choke must be set properly to work correctly. It is a bi-metallic part located behind the muffler. Heat from the muffler holds an air vane in the open position. Someone else probably has a more technical explanation but that's pretty much the jist of it.

 

[Rivets]

There is no choke at all for this style of carb. The primer is used instead of a choke. I hate to say this, but if you don't understand how this works, please don't take it apart and rebuild it. You may end up with spending even more money that just a new diaphragm and gasket.

 

[barberino]

A quick run down was all I needed. I'm going to check for air leaks around the primer. A no choke, primer only is just a unmarked territory for me. I now understand how the air primer sends air pressure in the carburetor bowl, the air pressure sends the fuel to the throat. Thus acting like a choke.

And I believe there is another style of primer usually found on two strokes that actually delivers fuel, not air to the carburetor...adding to my confusion when I realized the primer didn't function this way at all.

Unfortunately, I wasn't able to develop the simple link I needed to connect these areas of confusion.

Wouldn't be my first carburetor rebuild if I were to proceed. I'm quicker than the service guys around me, and cheaper too even after the cost of mess ups:laughing:. For me, all part of the learning process. Thanks.

 

[Rivets]

This manual, section 3, may help you understand how you carb works.

http://dl.dropboxusercontent.com/u/12502267/B&S Service Manuals/01_270962SingleCylinderLHead.pdf

 

[barberino]

Overall handy reference, thanks.

 

[barberino]

Found break in air cleaner gasket, replaced, still malfunctioning. Replaced primer ($3.99 TrueValue), still malfunctioning. Carb rebuild (Kit #498260 $9.96 at TrueValue), works great. Thanks!