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...measure the difference between the max lift and “no” lift by spinning the motor around (using dial indicator).
Why not just do that? Presumably, you already have a 7.3L engine with a camshaft installed, and a dial indicator; right?
 

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I haven't ever seen mention of someone having a worn fuel pump cam lobe though.
That's my point: unless it's visibly worn all the way across the lobe, some part of it will be the original profile. But probably the whole thing.
...it cannot make the pump make enough pressure.
Then all you really need to do is see how far the pump follower has to travel to make pressure, and compare it to your cam's lobe. Other engines' cams' lobes aren't really relevant.
 

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...everything from the tank to the fuel bowl inlet has been eliminated...
Then it must be something between the inlet & outlet, like all the other loops & orifices & valves inside the filter bowl assembly. Try eliminating the bowl by feeding fuel directly to the pump's high-pressure inlet, and see how much pressure comes from the outlet during cranking. You'll have to come up with some way to connect the pressure gauge to the dead-headed outlet. Remember (as bugman mentioined) there's a valve inside the filter's stand-pipe NOT indicated on this diagram:

 

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IDK the real name, but it's the plastic tube in the center of the filter bowl. I found out almost the hard way that it's left-hand-threaded into the bowl, with the heater plate held between. But there's a spring-loaded valve in the top of the plastic tube.

Light Circuit component Automotive tire Motor vehicle Coil


It leaks a little fuel when it's closed, but it's an obvious restriction.

Automotive lighting Gas Auto part Circuit component Circle


Glad to hear someone is still getting some use from SMN.
 

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