V4 fuel pump diaphragm; supposed to be one spring or two?

[Alan]

Hello to all;
My vintage service manual seems to show two springs, one on either side of the fuel pump diaphragm, but my vintage parts catalog shows only one.
The catalog does seem to show two, "supports", (what I’ve heard called buttons) but just one spring.
Or I’m looking at this wrong, and invite corrections.
It would be great to find out the diaphragm IS supposed to have a spring on both sides, and the absence explains my high speed bogging issue.
All opinions welcome.
Appreciated;
Alan

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[frankr]

It indeed takes two springs, different lengths. The upper one in the picture is the chamber that does the actual pumping. The lower chamber is called an air dome, and it’s function is to smooth out the individual pumping pulses.

[Author]

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