If you’ve got a 96–98 truck with the 5.7 Vortec that cranks strong and won’t fire, here’s the number that settles most of these: key-on fuel pressure. The CSFI poppet injectors are spring-loaded — they physically stay closed until pressure forces them open. Spec is roughly 60–66 psi key-on. At 50 psi — pressure that would run plenty of other engines — these just crank.
That’s why so many of these trucks get a full tune-up, a coil, and a relay before anyone puts a gauge on the rail.
Full diagnosis order (pressure test, bleed-down, filter, and the spider upgrade decision): 96–98 Vortec 5.7 No-Start: CSFI Fuel Pressure Diagnosis
Let’s collect real numbers and outcomes:
- What did your gauge read key-on when it wouldn’t start?
- What was the actual fix — pump, filter, regulator, or injectors?
- Anyone done the MFI spider upgrade? How many years/miles on it now, and would you do it again?
- Best “I threw parts at it before testing pressure” confession welcome. No judgment — most of us have one.