2002 GMC Sierra 3500 5.7L Engine P0335 and P0300 Issues - Stalling, Jerking, Fuel Pressure Low
My 2002 GMC Savanna 3500 with a 5.7L V8 engine is experiencing severe driving issues: the vehicle starts to buck, jerk, stumble, and lose power while on the road. It occasionally stalls completely. When I pull over, it restarts smoothly for a few minutes before the symptoms return. I've checked the OBD2 codes and found P0335 (Crankshaft Position Sensor A Circuit Malfunction) and P0300 (Random/Multiple Cylinder Misfire). I replaced the crankshaft position sensor (CKP), which provided temporary improvement, but as soon as the engine warms up, the bucking, jerking, and stalling return. Fuel pressure readings are currently between 49-51 psi. The manufacturer specifications for this engine series (CPI/CSFI/MPI) typically require fuel pressure to be above 60–65 psi for proper operation. Given that both P0335 and P0300 can be linked to low fuel pressure or fuel delivery issues, I suspect the root cause may lie here. I'm seeking advice on whether I should check the fuel filter, verify the exact fuel pressure specification for my engine type, and perform a CKP variation learn procedure after sensor replacement. Any insights would be greatly appreciated.
The symptoms—stalling, jerking, and misfiring—are consistent with low fuel pressure. For the 2002 GMC Savanna 3500 5.7L engine (CPI/CSFI/MPI series), verify the manufacturer-specified fuel pressure range. A reading below 60 psi is likely insufficient to maintain stable combustion, especially under load or at higher temperatures. P0300 and P0335 can both be triggered by low fuel pressure, leading to inconsistent engine performance and misfires. Since your current reading is around 49–51 psi, this supports the theory that fuel delivery may be inadequate. Additionally, ensure you've completed the CKP variation learn procedure after replacing the crankshaft position sensor—this is a required step for proper sensor calibration and accurate timing signal detection.