<VV> Fuel pump dissection

[Doug Mackintosh]

I had posted a couple weeks back about my mechanical fuel pump which had dumped gas into the crankcase. I have now dissected the offending pump. All diaphragms had reinforcing fibers, and while some had a few surface cracks, I could find no evidence of cracks actually passing through the material. The only thing I found of significance was that the bottom casting (the thin one) was distorted so when the bottom casting is mated with the central (valve body) casting there are gaps around the outside sealing interface (between the screw bosses) and around the seal area at the ID. I laid a straightedge across the lower casting and could insert a .010" feeler between the straightedge and the seal area at the ID of the diaphragm when the straightedge was placed across screw bosses. 
   
  Most likely, fuel leaked between the upper surface of the bottom diaphragm and the valve body casting at the inner seal, allowing fuel to flow into the pushrod area, flooding the recess until it overflowed the dam, then flowing into the crankcase. 
   
  I still do not understand why it didn't also squirt out the leak vent slot in the back. Can anyone explain that?
   


-- Doug Mackintosh
  Corsa member since 1996
  Corsa/NC member since 1996,  Virtual Vairs member
  Corvair owner 1969-1971 and 1996-on
 		
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