LISBON, Portugal — Portuguese tanker truck drivers have announced a new walkout, just days after returning to work and resuming talks with employers in a pay dispute.The Hazardous Materials Drivers Union said Wednesday its about 750 members — from a total of some 900 in Portugal — will refuse to work overtime and on weekends and public holidays Sept. 7-22.The union says truckers work many overtime hours to keep the country’s 3,000 gas stations stocked.Truckers ended a seven-day walkout on Sunday, after government emergency measures prevented gas pumps from running dry. Talks with employers broke down late Tuesday.A spate of strikes has tested the Socialist government, traditionally sympathetic to trade unions. But with a general election less than two months away, the centre-left is wary of taking sides.The Associated Press