Canada - Fuel System - Hard Starting After Fill Up

GROUP
FUEL

NO.
00-30-001

DATE
MARCH 31100

MODEL
SONATA EF

SUBJECT

HARD STARTING / ROUGH IDLE
AFTER FUEL FILL UP

Hyundai Auto Canada's Technical Assistance Centre (HY-TAC) has this repair tip for certain 1999 and 2000 MY 2.4 litre Sonata EFs manufactured from Job # 1 up to and including November 17, 1999 that may experience hard starting or rough idle after filling up with fuel.

HY-TAC has had success correcting this condition by examining the Evaporative Emission Control System's Purge Control Valve.

During normal operation, the ECM commands the purge control solenoid valve to open and close, depending on the throttle angle and vacuum in the intake manifold. When the purge valve opens, a controlled vacuum leak is created and fuel vapours from the charcoal canister are drawn into the intake manifold and then burned in the combustion chamber. To compensate for the richer air/fuel intake charge, and to ensure that the stoichiometric 14.7:1 air/fuel ratio is maintained, the ECM adjusts the injector pulse width accordingly.

If the purge valve is stuck in the open position, an uncontrolled vacuum leak is created. With a full tank of fuel, the fuel vapours become denser and are immediately drawn into the combustion chamber as the vehicle is trying to be started. Because the ECM is unaware of the extra fuel in the air/fuel mixture, the injector pulse width is not adjusted to accommodate it, thereby flooding" the cylinders causing the engine to have difficulty starting and a rough idle. Due to the broad variations in Canadian altitudes, operating conditions, fuel quality, and driver operating styles, the Malfunction Indicator Lamp (MIL) may not always illuminate, nor store a Diagnostic Trouble Code (DTC) in the E/TCM's memory.

The Purge Control Valve for the 2.4 litre Sonata EF (see production range above) has been improved and is currently available from Hyundai Auto Canada's PDC through your usual ordering procedures. The part number remains unchanged.