Car parked for 1 month, would not start,no pressure at the fuel reg at valve

we dont have this engine here, USA.
but i have the WG jeep book,
starting page 12 , chapter 14


FUEL INJECTION PUMP BLEEDING
(1) If the fuel injection pump has been replaced,
air should be bled at the overflow valve before
attempting to start engine.
(a) Loosen the overflow valve (Fig. 18) at the
rear of the injection pump.
(b) Place a towel below the valve.
WARNING: WHEN CRANKING THE ENGINE TO
BLEED AIR FROM THE INJECTION PUMP, THE
ENGINE MAY START. PLACE THE TRANSMISSION
IN NEUTRAL OR PARK AND SET PARKING BRAKE
BEFORE ENGAGING THE STARTER MOTOR.
CAUTION: Do not engage the starter motor for
more than 30 seconds at a time. Allow 2 minutes
between cranking intervals.
(2) Crank the engine for 30 seconds at a time to
allow air trapped in the injection pump to vent out
the fuel injector drain tubes. Continue this procedure
until the engine starts. Observe the previous WARNING
and CAUTION.
(3) Tighten overflow valve.
HIGH-PRESSURE FUEL LINE BLEEDING
WARNING: THE INJECTION PUMP SUPPLIES HIGH-
-PRESSURE FUEL OF APPROXIMATELY 45,000 KPA
(6,526 PSI) TO EACH INDIVIDUAL INJECTOR
THROUGH THE HIGH-PRESSURE LINES. FUEL
UNDER THIS AMOUNT OF PRESSURE CAN PENETRATE
THE SKIN AND CAUSE PERSONAL INJURY.
WEAR SAFETY GOGGLES AND ADEQUATE PROTECTIVE
CLOTHING AND AVOID CONTACT WITH
FUEL SPRAY WHEN BLEEDING HIGH-PRESSURE
FUEL LINES.
WARNING: DO NOT BLEED AIR FROM THE FUEL
SYSTEM OF A HOT ENGINE. DO NOT ALLOW FUEL
TO SPRAY ONTO THE EXHAUST MANIFOLD WHEN
BLEEDING AIR FROM THE FUEL SYSTEM.
Bleed air from one injector at time.
(1) Loosen the high-pressure fuel line fitting at
the injector (Fig. 19).
(2) Crank the engine until all air has been bled
from the line. Do not operate the starter motor
for longer than 30 seconds. Wait 2 minutes
between cranking intervals.
(3) Start the engine and bleed one injector at a
time until the engine runs smoothly.

end quote.
pump timing is on next page
or tank filter line priming before. above.

the fuel rail always does that. that is its #1 job. to hold a steady pressure (until vacuum drops)
that is the job of the fuel pressure regulator.
i see you work with no tools? or gauges? the fuel pressure test is first.
not the map , the map, is like a rock, lasts near for ever.
but not any PFreg.
the FSM covers the reg tests.
i do these , (PSI spec tests) (by the book below and ASE books)

• cranking pressure.
• ildling pressure.
• gun the throttle pressure , huge vacuum drop and pressure drops lower by about 6PSI , from cranking pressure.
• I then cut the throttle and vacuum hits near 26inches and the fuel pressure drops to its most lowest now, (reg action) does it?

https://www.techauthority.com/en-US/Pages/Home.aspx

going backwards, ? (yes, i to check volts first) but...
you check fuel pressure cranking, (is press in spec or not?)
the FSM covers this, 1/.2 the cars only get pump activation,,
cranking and running, never just key on (the fsm shows this fact, i didnt look for you)
Yours is older loop system, not dead head.
there are 5 test just for the pump, (actually more)
pressure cranking and running, (leakdown test and injector balance tests and shut test for loop version) on V6 that 6 +4 ,10 total tests.
once the gauge is in place we do all 10s tests on v6.

ok say my pressure spec. is 40psi cranking and i get 10.?

spec: 32-40 running, pSI, vac, hose conn. (cranking will be more)
in loop systems the cranking pressure is about 10 PSI more.
after it starts, the vacuum sucks pressure from say 50psi to 40.
(its also altitude compensating)

Voltage checks, (any voltmeter)
use a voltmeter to see if full power reaches the pump.
i check voltage and its 8v. (bad) cranking volts can be near 11v due
to battery load, 200amps or so... what i do is measure battery crank
voltage and expect same to pump , using the 0.5v rule. (drop)
the connector over here to pump is all corroded. ,,
fix that and bam, now full presssure
or i find a bad fuel pump relay, replace that and bam.
or i find 0v, to pump.
i find relay bad. (simple tests on relay) (its not bad ECU)
ok i find 12v. at pump. so what is wrong?, i check my fuel pressure
regulator at the fuel rail, its stuck wide open because the shunt test
passed (one of 4 tests above) so new reg and bam, 40psi to rail.
i can test the reg with my hand vacuum tool that all shops have.
i can see pressure, running and cranking and check fuel pressure
with no vacuum (50psi?) then pump it to say 20 "hg (simulates idle)
and see 40 pSI, and check the diaphram for leak down.
my reg was bad.
there are other tests:
1: fuel pump current. (if excessive, its a bad pump)
2: scope test or use a current probe on pump and see it spiking
like made, , it has bad commutator and will die so.

there great videos on all this at. Duane's site.
http://www.youtube.com/results?search_query=fuel%20pump&sm=3

check the pump cranking

do not hot wire the fuel pump relay
if you slip 1/.8" you blow up a nice $400 ECU, (or more)
the ECU drives this relay (with a transistor, you dont want to explode)
if you feel compelled to hot wire things, disconnect the pump
and hot wire that.
now the relay.
it has 4 pins 12vdc in, 12vdc out to pump (contacts)
and 2 coil pins.
you put your meter to coil pins (across) i get 12v to coil cranking and running, that is the ECU working right
i get 12vdc in and zero out the contacts, the relay is bad.
lets say you see 3v out, that can be a shorted pump. or wire grounded out to pump. I check the current with my amp clamp and see 15amps
the pump is bad. most draw 4-6amps. normal.
i keep an open mind, what is bad, its only the pump 1/2 the time
or less. maybe 1/3? (reg, pump, wires and friends)
corroded connectors big time...some even burned up.

check fuel pressure

Filter or pickup is probably clogged.

i know pressure reg. is new but its bad. try when first crank up put a vacuum pump on reg. if pressure drops then drop replace it

could be the pump? or the pump relay? or even a clogged fuel filter crack the line going into the rear of the filter and crank the motor if fuel comes out ? change the filter if no fuel then? check the relay and or change the pump

regulator if you have good pressure at the valve. when you turn the key on can you hear the fuel run for 10-20 seconds? take off vacuum line from the fuel pressure reg. is there gas that comes out the reg/vacuum hose? if so its the regulator!!

No, the fuel pressure valve may be stuck open so that the fuel pressure is too low when you start up, but the pump keeps up after the engine starts...
The fuel pressure valve is draining the fuel back into the fuel tank when the Blazer is parked.

Had one of these drive me crazy. That one was the fuel pump. Pumped OK, but let the pressure back into the tank and let air into the fuel rail. Once engine had cooled,the pump purged the air out of system. Have someone check the fuel pressure when it does not start. If check valve is bad,there will be lots of air in the fuel rail. Second most likely cause is crank sensor going bad.It becomes heat sensitive on the way out.