13.5 while running
11.5 while cranking at the high pressure pump
And it won’t start .
i changed the fuel filter today .

 

Other observations :
if I feather the gas pedal just right I can prevent it from stalling while idling .
if I force the fuel pump to run by jumping it at the relay the pressure is at 40 psi with the engine off
with the engine running 32 psi at the rail perhaps a little low ?
I noticed the fuel return supply line on the rail has a kink in it . Perhaps restricting flow ?

 

I am trying to come up with checks you can see right away.what you have or don't have.

Can you do this, when it will not start, and you cranked it some, remove a spark plug and see if it is wet with fuel or dry. . If wet, no spark. If dry no fuel. Then we have some idea of where to go next.

 

I will give the spark plug deal a try .
not sure what the diagnostic plug looks like .

 

Just type in 1989 Ford diagnostic plug, and there are pictures and explanations of how to use it for diagnosis..