Fuel pump and pressure regulator issues will show up with a fuel pressure test. You won't get anywhere without a couple fairly inexpensive diagnostic tools.
Get a GM TBI fuel pressure test tap that replaces the fuel filter temporarily for diagnostics.
Tool Aid TBI Fuel Pressure Test Adapter 37650...
And a fuel pressure test gauge... Like this one.
OTC 5630 Fuel Pressure Test Gauge
If you have below 12PSI then block the return line by carefully pinching the rubber return hose with a pair of needle nose pliers.
If the pressure builds up replace the fuel pressure regulator.
If it's still lower than 12PSI check for leaks between the sender and the fuel filter connection. If there are no leaks replace the fuel pump and tank sock... I've seen the steel sender lines inside the tank perforate from rust so pay attention when you pull it.
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1959 M35A2 LDT465-1D SOLD
1967 Dodge W200 B383, NP420/NP201 SOLD
1969 Dodge Polara 500 B383, A833 SOLD
1972 Ford F250 FE390, NP435/NP205 SOLD
1976 Chevy K20, 6.5L, NV4500/NP208 SOLD
1986 M1008 CUCV SOLD
2000 GMC C2500, TD6.5L, NV4500
2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263
2009 Impala SS LS4 V8
RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials...
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