<VV> The YH Pump - my final answer

[Dennis PLEAU]

Hopefully the formatting holds together this time.  I hate hotmail.
 
This answer brings up a lot of questions.  Inserted in your text



 From: gyoungwolf at earthlink.net  Let me hopefully prevent some hysteria about the function of the YH accelerator pump. I am going to quote this from the Carter YH manual so as not to be defamed:  "The accelerator pump circuit provides a measured amount of fuel, which is necessary to insure smooth engine operation for acceleration at speeds below approximately 30 MPH. (P) Accelerating pump action is controlled both mechanically and by manifold vacuum in the same manner as the metering rod. When the throttle is closed, the diaphragm moves downward and fuel is drawn into the pump fuel chamber through the intake check.  >>>>>Does the mechanical connection or the manifold vacuum move the diaphragm down? >>>>Is there a rod or something connected to the diaphragm that moves it down or is it only the vacuum? The discharge check is seated at this time to prevent fuel from the nozzle passage being drawn into the pump chamber. When the throttle is opened, the diaphragm moves upward forcing fuel out through the discharge passage, past the discharge check, and out of the pump jet, which directs the fuel up the nozzle passage and out the end of the nozzle.....If the throttle is opened suddenly, the upper pump spring will be compressed resulting in a smoother pump discharge of longer duration." >>>>>Is this spring the mechanical connection?  So yes, Virginia, there is a squirt if you pump the accelerator rod....the prosecution rests... The CarbmeisterDennis "too many years playing and engineer to accept this answer" Pleau
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