Failure mode - GM 8.1L / 6.0L Vortec Gasoline (HD 2001-2007, Express/Savana vans incl.)

Hard cold start / fuel delivery wear

Reliability tier: aggregated - verify before ordering, see /disclosure/

Symptoms

extended crank when cold, sometimes needing multiple tries
pump prime weak or absent at key-on; pressure bleeds down quickly after shutdown
worse in cold weather

Compare with the other causes of the same sign on this engine: hard start, long crank or no-start

Root cause

The owner record puts most hard-cold-start cases on tired in-tank fuel pumps and rail pressure bleed-down (leaking injectors / regulator) rather than ignition. Verify pump prime and hold pressure before parts-cannoning.

Diagnosis

listen for the pump prime at key-on; gauge the rail pressure (hold ~50-60 psi after key-off)
rule out rusted lines and a tired pressure regulator
check for injector wash-down (smell, wet plug) on long-crank trucks

Fixes

repair: in-tank pump module, regulator, or injector service per findings ()

fuel-pump - more than one option: GM HD In-Tank Fuel Pump Module 2001-2003 (OEM), GM HD In-Tank Fuel Pump Module 2004-2007 (OEM)
fuel-injector - more than one option: 6.0L Vortec Fuel Injector (OEM), 6.0L Vortec HD Fuel Injector Assembly (OEM), 8.1L Vortec Fuel Injector (OEM)
GM Truck Fuel Pressure Regulator Kit (OEM)

Prevalence

common

Parts for this repair run about $35-$220: see them next to the other repairs on this engine in repair costs.