I have a walbro wj carb off a Poulan saw and i am curious about how the spring loaded plunger works .I see one passage leads to the main nozzle,i am not sure how this plunger unseats ,is this some type of accelerater pump.Any info appreciated.Thanks
walbro wj
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jokers
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Hi wgr
It sounds to me like you are asking how the inlet needle works.
Engine vacuum through the throat of the carb pulls the fuel either through a combination of the idle circuit holes or through a combination of idle circuit holes and the Hi speed nozzle. This "pull" through any of these fuel circuits acts on the metering diaphragm, which is a force multiplier capable of overcoming the spring under the inlet lever. As force is applied to the lever via the metering diaphragm, the fuel inlet needle is lifted allowing more fuel to enter the carb venturi, thus engine speed and output is increased. It`s a good idea to replace the metering diaphragm more often than the rest of the carb would need attention. These diaphragms can get stretched or stiff and won`t work properly.
BTW, for everyone else, I know that I left out a few minor details that seemed unimportant to this description.
So there, is it clear as mud now?
Russ
It sounds to me like you are asking how the inlet needle works.
Engine vacuum through the throat of the carb pulls the fuel either through a combination of the idle circuit holes or through a combination of idle circuit holes and the Hi speed nozzle. This "pull" through any of these fuel circuits acts on the metering diaphragm, which is a force multiplier capable of overcoming the spring under the inlet lever. As force is applied to the lever via the metering diaphragm, the fuel inlet needle is lifted allowing more fuel to enter the carb venturi, thus engine speed and output is increased. It`s a good idea to replace the metering diaphragm more often than the rest of the carb would need attention. These diaphragms can get stretched or stiff and won`t work properly.
BTW, for everyone else, I know that I left out a few minor details that seemed unimportant to this description.
So there, is it clear as mud now?
Russ
I have been trying to reason out this question. I checked with my repair manual and it states the wj does not have an accelerator pump. So what could it be that you are refering to? I think it may be a govenor. Is it a brass/metal screw-in piece that has a spring and check ball inside? These are made to unseat at a predetermined RPM and enrichen the circuit to slow the engine. Good protection for over-reving but when they get old and the spring loses some tension, they tend to come on too soon and the saw is not as powerful. Mike
I've been wondering what exactly was asked too.
wgr, visit <a href="http://www.aerocorsair.com/id27_m.htm">http://www.aerocorsair.com/id27_m.htm</a> and let us know if what you're talking about is represented there, and if so, exactly what using the terms in the diagrams. We'll walk you through it if that page doesn't help enough.
Russ did a pretty good job of describing the overall process, though there are some of us who often feel no detail is unimportant, no matter how small... (here, have some sand Russ).
Glen
wgr, visit <a href="http://www.aerocorsair.com/id27_m.htm">http://www.aerocorsair.com/id27_m.htm</a> and let us know if what you're talking about is represented there, and if so, exactly what using the terms in the diagrams. We'll walk you through it if that page doesn't help enough.
Russ did a pretty good job of describing the overall process, though there are some of us who often feel no detail is unimportant, no matter how small... (here, have some sand Russ).
Glen
jokers
Addicted to ArboristSite
Thanks Glen!
Russ
Russ
I made a mistake on the saw it is a pioneer,it is a wj and my service manual shows no accelerater pump on a wj .the carb has a govenor, but this plunger is seperate, it is located on the bottom left side of carb choke side.The plunger is held in with a brass screw and uses a spring to keep the plunger seated.When i go back to the shop i will trace the passages to the plunger. Thanks for the info
Go to <a href="http://wem.walbro.com/walbro/group2.asp?FamilyName=WJ">http://wem.walbro.com/walbro/group2.asp?FamilyName=WJ</a> and pick any carb listed if you don't see your specific model. They all display the same image
<img src="http://wem.walbro.com/walbro/CategoryImages/WJ.jpg">
with a common part list description. Some carbs have some of the parts and others don't, and the specific part numbers vary, naturally. The WJ-5-1, WJ-20-1, WJ-21-1, WJ-38-1, and WJ-49-1 are the models showing the "accelerator kit" as part of their makeup.
The 20, 21, and 49 all have both the accelerator (item 61, about 7 o'clock) and the governor (item 18, about 3 o'clock). The brass screw you mention sure sounds like that (item 24) retaining the accelerator kit.
I can't help other than this info, but I'd sure like to know what you come up with.
Glen
<img src="http://wem.walbro.com/walbro/CategoryImages/WJ.jpg">
with a common part list description. Some carbs have some of the parts and others don't, and the specific part numbers vary, naturally. The WJ-5-1, WJ-20-1, WJ-21-1, WJ-38-1, and WJ-49-1 are the models showing the "accelerator kit" as part of their makeup.
The 20, 21, and 49 all have both the accelerator (item 61, about 7 o'clock) and the governor (item 18, about 3 o'clock). The brass screw you mention sure sounds like that (item 24) retaining the accelerator kit.
I can't help other than this info, but I'd sure like to know what you come up with.
Glen
