[alfa] FISPA device

["John Hertzman" <johnhertzman@xxxxxxxxxxxxx>]

Kevin Trent asks about a pair of "FISPA devices" in the fuel system of a Spica Spider he is resuscitating; Farszan suggests that they are "just regular check valves.  They block fuel backflow (potentially dirty) to the injection pump." I am not familiar with them or with their explanation, but something matching Kevin's description shows up in the 1980 Alfetta Catalogo Rapido (with a part number 11634.32033.00) as used on both the first and second series Alfetta Berlinas (as well as the coupes) but does not appear in the 1975 Alfetta parts book I have, ergo would seem to be a 1976-77 introduction. They are shown with one in the line from the main filter to the injection pump, arrow pointing toward the injection pump, and the other in the return line from the pump to the tank, arrow pointing away from the injection pump toward the tank.

If Kevin's initial description is correct ("if you blow into it in the direction of the arrow, it will "hold" then release and pass flow when sufficient force is applied.  If blown from the opposite side it will not release") it would seem to me that they would maintain a modest amount of fuel at and in the injection pump with the engine and fuel pump off, preventing any drainback from the injection pump to the tank. This is idle speculation about a part I have never noticed or heard of, but it is my best guess. Farszan's proposal that they block potentially dirty backflow to the injection pump seems less likely, as the return line dumps in the top of the tank, creating an airgap in all except a brimfull tank, and the second device, between the filter and the pump, would be unexplained. Neither explanation would exclude the other, however, and there may still be more and better ones.

Mies van der Rohe used to suggest that behind every decision there will be a real reason, and that there should always be at least one good reason; and sometimes they will be the same.

Enjoy yours,

John H.
Raleigh, N.C.
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