For a while now my 91 Dak (5.2 V8, dual-port throttle body injection, auto trans) has had these 'episodes' where it won't start or quits running.
Sometimes it'll restart after a half-hour, sometimes after 5 min, sometimes overnight. Still has spark. The problem seems to coincide with fuel level below about 1/3 full. When the problem is present, I can hear the 'whirring' noise of the fuel pump running if I listen at the filler neck while cranking the motor. Whether or not the problem is present, the computer code is always "31" which I understand is an EGR solenioid message; I don't think this is related to the problem.

Desperate for more info, I installed a fuel pressure gauge. When the truck is running, the fuel pressure reads 15 PSI, but this morning the truck wouldn't start, and fuel pressure reads 10 PSI.

I'm a little suprised by this result - I expected full pressure or no pressure, not 'partial' pressure. Does the computer watch the fuel pressure? Do the injectors need full 15 PSI to force them open? Weird.

Q: Based on this info, would you replace the fuel pump? Is there some other component that might be at fault?

Thanks!

My truck use to have problems starting, and I also noticed a loss of power, the gas gauge also did not work, to solve these problems i replaced the fuel pump assembly, and and had the injectors cleaned, it turned out two of them were nearly completely clogged.
hope this helps