TECHNICAL FIELD

Various embodiments relate to a vehicle fuel system with a recirculation line.

BACKGROUND

A fuel system for a vehicle has a fuel tank with a fuel fill port. The fuel tank may be periodically filled or refueled via the fuel fill port. The fuel system may additionally be connected by a vapor line to an evaporative emissions system with a canister to adsorb fuel vapors. The fuel system may be provided with a recirculation line connecting the vapor line to the fuel fill port to recirculate fuel vapor during refueling to reduce air entrainment and reduce further vaporization of fuel within the tank.

SUMMARY

In an embodiment, a fuel system is provided with a fuel tank, and a fuel fill inlet fluidly connected to the fuel tank to receive fuel dispensed from an external fuel supply device. A recirculation line has a first end fluidly connected to the fuel fill inlet and a second end fluidly connected to the fuel tank. An ejector is positioned within the recirculation line, and a valve is positioned within a drain line fluidly connecting the ejector to the fuel tank. A pressure sensor is positioned to measure a pressure associated with the drain line between the ejector and the valve. A controller is in communication with the pressure sensor, and the controller configured to, in response to initiation of a refueling event, determine a state of the valve based on the pressure.

In another embodiment, a method of fueling a vehicle is provided. Liquid fuel is dispensed into a fuel tank via a fuel fill inlet. Vapor is recirculated from the fuel tank to the fuel fill inlet via a recirculation line with an ejector in response to the liquid fuel being dispensed. A vacuum is drawn on a check valve via the ejector thereby maintaining the check valve in a closed position to prevent fluid flow through a drain line and the check valve, with the drain line fluidly connecting the recirculation line and the fuel tank. A pressure in the drain line between the ejector and the check valve is monitored while the liquid fuel is being dispensed to determine a position of the check valve. A flag associated with the check valve is set in response to the pressure being less than an atmospheric pressure.

In an embodiment, a vehicle is provided with a fuel tank and a fuel fill inlet fluidly connected to the fuel tank to receive fuel dispensed from an external fuel supply device. A recirculation line has a first end fluidly connected to the fuel fill inlet and a second end fluidly connected to the fuel tank. An ejector is positioned within the recirculation line. A check valve fluidly connects the ejector to the fuel tank via a drain line such that the ejector draws suction on the check valve to maintain the check valve in a closed position in response to vapor flow through the recirculation line and ejector during fueling of the fuel tank, and liquid fuel in the recirculation line drains into the fuel tank via the check valve and the drain line. A pressure sensor is positioned to measure a pressure in the drain line between the ejector and the check valve. An evaporative emissions system has a fuel vapor canister, with the evaporative emissions system fluidly connected to the recirculation line between the ejector and the second end via a control valve. A controller is configured to, in response to initiation of a refueling event, monitor the pressure, set a first flag associated with the check valve in response to the pressure being less than an atmospheric pressure prior to pulsing the control valve, pulse the control valve, and set a second flag associated with the check valve in response to the pressure being greater than the atmospheric pressure subsequent to pulsing the control valve.

