Some of the WVO vendors have started selling the aux fuel pumps to be wired to run continually for quicker heatup, so it might be worth experimenting with. This might relieve the pressure enough for nomal monovalve function. Be sure to install an inline fuse (do a search for correct amps, but 1 or 2 amp as I recall) as a precaution. And report back.

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1983 CD
1958 Studebaker Packard (being resuscitated)