Hydrocarbon vapor start techniques using a purge pump and hydrocarbon sensor

An evaporative emissions (EVAP) control system for a vehicle, the system comprising:

• a purge pump configured to pump fuel vapor trapped in a vapor canister to an engine of the vehicle via a vapor line and a purge valve when engine vacuum is less than an appropriate level for delivering fuel vapor to the engine, the fuel vapor resulting from evaporation of a liquid fuel stored in a fuel tank of the engine;
• a hydrocarbon (HC) sensor disposed in the vapor line and configured to measure an amount of HC in the fuel vapor pumped by the purge pump to the engine via the vapor line;
• and
• a controller configured to:
• detect an imminent cold start of the engine by detecting a set of cold start preconditions that are each indicative of the imminent cold start of the engine, wherein one of the set of cold start preconditions includes (i) a key-on event has occurred that is indicative of an engine-off to engine-on transition, (ii) the purge pump has spooled to greater than a minimum speed threshold, and (iii) the HC sensor is on;
• and
• in response to the detecting, perform the cold start of the engine by controlling at least one of the purge pump and the purge valve, based on the measured amount of HC, to deliver a desired amount of fuel vapor to the engine,
• wherein delivery of the desired amount of fuel vapor during the cold start of the engine decreases HC emissions by the engine.