Hard Start / Starts Then Dies on Cold Engine
The engine starts but stalls immediately when cold, indicating a fuel delivery or air/fuel mixture issue. This is common on 2020 Silverado 1500 models with the 5.3L or 6.2L V8 engines, often related to fuel pressure loss or sensor malfunction.
Diagnosis Details
Possible Causes
Fuel pump or fuel pressure regulator failure – loss of residual fuel pressure allows air into the system, causing hard cold starts and stalling.
Engine coolant temperature sensor (ECT) or intake air temperature sensor (IAT) sending incorrect signal, causing overly lean or rich mixture on cold start.
Throttle body carbon buildup or idle air control (IAC) valve sticking, preventing proper idle after start.
Related OBD-II Codes
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What You Should Do
Check fuel pressure with a gauge after the engine sits overnight (should hold near 55-62 psi).
If pressure drops quickly, replace fuel pump assembly.
Scan for diagnostic trouble codes (DTCs) related to coolant temp or throttle position.
Clean throttle body and IAC passage if carbon is present.
Related Repairs
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Disclaimer: This AI-generated diagnosis is for informational reference only. Always consult a qualified mechanic for an in-person inspection. AutOwner is not responsible for decisions made based on this information.
