# US 8,739,605 B2 · System and method for diagnosing faults in vacuum pumps of fuel systems and for diagnosing leaks in fuel systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,739,605 B2 - Document ID: US8739605B2 - Status: Granted - Kind: B2 - Application number: 12/952,522 - Filed: 2010-11-23 - Published: 2012-04-26 - Granted: 2014-06-03 - Earliest claimed: 2010-10-21 - Assignees: GM Global Technology Operations LLC - Applicants: Kurt D. McLain; William R. Cadman - Inventors: Kurt D. McLain; William R. Cadman - Web page: https://patentgrep.com/patent/US8739605B2 ## CPC - F02M 25/0809: {Judging failure of purge control system} - F02D 41/0032: {Controlling the purging of the canister as a function of the engine operating conditions} - F02D 2041/225: {Leakage detection} - Y10T 137/0318: Processes - Y10T 137/7837: Direct response valves [i.e., check valve type] - F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A control system includes a switching valve control module, a pressure determination module, and a fuel system diagnostic module. The switching valve control module actuates a switching valve in a fuel system of a vehicle between a first position and a second position, the first position venting a suction side of a vacuum pump in the fuel system to an atmosphere, the second position sealing the suction side of the vacuum pump from the atmosphere. The pressure determination module determines a first pressure on the suction side of the vacuum pump when the switching valve is in the first position, and determines a second pressure on the suction side of the vacuum pump when the switching valve is in the second position. The fuel system diagnostic module selectively diagnoses a fault in the vacuum pump based on the first pressure and the second pressure. ## Claims ### Claim 1 A control system, comprising: a switching valve control module that actuates a switching valve in a fuel system of a vehicle between a first position and a second position, the first position venting a suction side of a vacuum pump in the fuel system to an atmosphere, the second position sealing the suction side of the vacuum pump from the atmosphere; a pressure determination module that: determines a first pressure on the suction side of the vacuum pump when the switching valve is in the first position; and determines a second pressure on the suction side of the vacuum pump when the switching valve is in the second position; and a fuel system diagnostic module that selectively determines that the vacuum pump is stuck on based on the first pressure and the second pressure. ### Claim 2 (depends on 1) The control system of claim 1, wherein the fuel system diagnostic module determines that the vacuum pump is stuck on when a first difference between the first pressure and the second pressure is greater than a first threshold. ### Claim 3 (depends on 2) The control system of claim 2, wherein the fuel system diagnostic module determines the first threshold based on a flow capacity of the vacuum pump. ### Claim 4 (depends on 1) The control system of claim 1, wherein the pressure determination module determines the first pressure when the vehicle is off for a predetermined period. ### Claim 5 (depends on 1) The control system of claim 1, further comprising a pump control module that controls the vacuum pump, wherein the pressure determination module determines the first pressure and the second pressure when the vacuum pump is commanded off. ### Claim 6 (depends on 1) The control system of claim 1, further comprising a vent valve control module that controls a vent valve in the fuel system, wherein the pressure determination module determines the first pressure and the second pressure when the vent valve is commanded closed. ### Claim 7 (depends on 1) The control system of claim 1, further comprising a purge valve control module that controls a purge valve in the fuel system, wherein the pressure determination module determines the first pressure and the second pressure when the purge valve is commanded closed. ### Claim 8 (depends on 7) The control system of claim 7, wherein: the pressure determination module determines a third pressure when the switching valve is in the first position and the vacuum pump is commanded on; the pressure determination module determines a fourth pressure when the switching valve is in the second position and the vacuum pump is commanded on; and the fuel system diagnostic module selectively diagnoses a leak in the fuel system when a second difference between the third pressure and the fourth pressure is less than a second threshold. ### Claim 9 (depends on 8) The control system of claim 8, wherein the fuel system diagnostic module determines the second threshold based on at least one of the first pressure, the second pressure, and the third pressure. ### Claim 10 (depends on 8) The control system of claim 8, wherein the fuel system diagnostic module refrains from diagnosing a leak in the fuel system when the fuel system diagnostic module diagnoses a fault in the vacuum pump. ### Claim 11 A method, comprising: actuating a switching valve in a fuel system of a vehicle between a first position and a second position, the first position venting a suction side of a vacuum pump in the fuel system to an atmosphere, the second position sealing the suction side of the vacuum pump from the atmosphere; determining a first pressure on the suction side of the vacuum pump when the switching valve is in the first position; determining a second pressure on the suction side of the vacuum pump when the switching valve is in the second position; and selectively determining that the vacuum pump is stuck on based on the first pressure and the second pressure. ### Claim 12 A method, comprising: actuating a switching valve in a fuel system of a vehicle between a first position and a second position, the first position venting a suction side of a vacuum pump in the fuel system to an atmosphere, the second position sealing the suction side of the vacuum pump from the atmosphere; determining a first pressure on the suction side of the vacuum pump when the switching valve is in the first position; determining a second pressure on the suction side of the vacuum pump when the switching valve is in the second position; selectively diagnosing a fault in the vacuum pump based on the first pressure and the second pressure; and determining that the vacuum pump is stuck on when a first difference between the first pressure and the second pressure is greater than a first threshold. ### Claim 13 (depends on 12) The method of claim 12, further comprising determining the first threshold based on a flow capacity of the vacuum pump. ### Claim 14 (depends on 11) The method of claim 11, further comprising determining the first pressure when the vehicle is off for a predetermined period. ### Claim 15 (depends on 11) The method of claim 11, further comprising determining the first pressure and the second pressure when the vacuum pump is commanded off. ### Claim 16 (depends on 11) The method of claim 11, further comprising determining the first pressure and the second pressure when a vent valve is commanded closed. ### Claim 17 (depends on 11) The method of claim 11, further comprising determining the first pressure and the second pressure when a purge valve is commanded closed. ### Claim 18 (depends on 17) The method of claim 17, further comprising: determining a third pressure when the switching valve is in the first position and the vacuum pump is commanded on; determining a fourth pressure when the switching valve is in the second position and the vacuum pump is commanded on; and selectively diagnosing a leak in the fuel system when a second difference between the third pressure and the fourth pressure is less than a second threshold. ### Claim 19 (depends on 18) The method of claim 18, further comprising determining the second threshold based on at least one of the first pressure, the second pressure, and the third pressure. ### Claim 20 (depends on 18) The method of claim 18, further comprising refraining from diagnosing a leak in the fuel system when a fault in the vacuum pump is diagnosed.