4kq fuel pump power circuit intermittent?? help

[Ragnampiza at aol.com]

My fuel pump circuit seems to have a mind of its own these days . just took
it on 300 mile trip and there were no problems. Let it sit overnight and no
start.
checked power to pump at the green/yellow wire connector under rear seat, and
reading was zero(while engine was cranking). traced wire all the way to #2
relay and there were no signs of cracking, breakage , overheating or shorts.
switched out relay with 2 different(known good) units -still zero. Replugged
connector , car starts right up with orig relay.  Drive 2 miles car dies dead
at 2500 rpm mellow cruise speed (35mph, smooth road).Cranks and cranks but
nada. check for power again zero . walk to autoparts store to buy  primary
wire to hard wire to defroster switch to limp it home. give it a crank BEFORE
emergency wiring procedure... it starts!

   All the fuel lines have been replaced and pump runs smooth and quiet.
my question is if its not the pump and not the wires not the connector and
not the relays what could it be?, I let the car idle at dead stop before
turning it off last night, but zero volts in the morning???...help please
before I'm stranded again.

I did not check for voltage before female connector under seat , I only stuck
the probe in ..currently reads 12v while cranking

I went through this stuff with the rad fan relay 2 years ago and I ended up
hardwiring a switch and eliminating the relay and I havent had a problem yet
and I save a ton of $$ by not replacing $20 relays every summer....barely
have to hit the switch in the winter or on the freeway.