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While my SPICA pump was at Wes's, I took an old, worn SPICA pump and installed in the sidelined motor. I got it to run (which surprised me) but I could never get it to smooth out and to my surprise I was belching as much blue smoke as I was black (ie alot of both). I had never known this engine to burn oil before so I was understandably bummed at the prospect of having to tear it down and rebuilt it. To my great relief, when I installed the rebuilt SPICA pump the blue smoke was gone (as well as the black smoke!).
Does it make sense that a worn SPICA pump could draw oil? Caould it be drawn up the little pistons much like worn rings in the cylinders?
 

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Change your oil before you drive any further! Leaky pump - gas in oil - makes oil thin - gets past rings - makes blue smoke. A leaky Spica can ruin your whole engine (from what I hear).

Bill
 

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I suppose a really badly worn pump could have oil get into the pump chamber. Oil pressure is about 50 psi, while the fuel pressure in the fuel gallery is no more than about 15 psi. As the plunger descends in the barrel and uncovers the fuel inlet, I suppose the oil pressure could overcome the worn fit between the plungers and barrels and get pumped to the injectors. See picture below. The fillet in the bore is the oil channel. "Sealing" of the plunger and bore is by close tolerance fit only. There are no "rings."
 

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