On the poulan 3750 I am tearing apart, there appears to be a fuel type line running from the right side carb (looking from backside) to the bottom left of the cylinder. What is a impulse line and whats its purpose.
What is a IMPULSE LINE?
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Al Smith
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The impulse,is what's referred to the positive crankcase pressure the engine generates ,when the piston is going in a downward position.By using the positive pressure,the diaphragm carb,basically pumps fuel,from the fuel tank.The fuel pump,with it's set of check valves,uses impulse,on one side,of the diaphragm,and atmospheric pressure ,on the other to generate this pumping action.Impulse pressure can also be used to operate oil pumps to oil the saw bar.{McCulloch}
it tranfers a part of the alternating high and low pressure conditions from the crankcase to the carb to run its fuel pumping feature
njforestfire
ArboristSite Operative
Perfect explanation you two!
Lawn Masters
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Well, hang around, and before you know it, you'll know as much as the rest of the guys. I just hang around for fun.
jimbo1490
ArboristSite Guru
The diaphragm carb and impulse feed are how you go about making a carb without a fuel bowl. Fuels bowl carbs are perfectly OK if you are not going to hold the thing sideways or upside down like we do with chainsaws. This is the reason these type of carbs dominate in the chainsaw market; they work in all positions
Jimbo
Jimbo
fishhuntcutwood
Full wraps and long bars!!!!!!!!!
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Timbermaster said:
Ah, saws are fun, and easy to work with when you get a little bit of knowledge under your belt, then you realize you want more, and seek it out, and before long you're doling out advice. And none of us here stop learning.
Take care all,
Jeff
