Thanks so much to everyone for adding to this discussion. I think I’m in over my head now, and I’ve already ordered a new fuel pump, so I’ll install that and see what happens. I will report back with results!
I understand…. “Too many cooks…..”. I’m not sure what you are trying to point out with the copied page from the service manual, although it is a little confusing. These pages cover several years of the 5.5hp engine. The earlier models used the pressure port, but the 1960 and newer models did not. If that nipple was actually present on the 1960 models, it would have been capped off or a threaded plug would be where the nipple is shown in this picture. That picture was probably taken from a 1959 model, I can tell by the location of the knobs/links and the fact that there are no engine cover bumpers mounted to the sides of the manifold for the older clam shell engine covers, along with the presence of the pressure outlet nipple on the manifold (item 4).
The manual should have clarified that the pressure nipple was not present, or not used (plugged or capped off) on the 1960 and later models.
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