However, the natural gas engine company, which reports in U.S. dollars, maintained its outlook for 2013 for revenue growth of 16 to 19 per cent to between $180 million and $200 million.
The company said Thursday the loss amounted to 57 cents per share for the quarter ended March 31 compared with a loss of $22.6 million or 44 cents per share a year ago.
Consolidated revenue for the quarter totalled $30.1 million, down from $36 million.
"As expected, our first quarter of 2013 was a transition period with remnant effects from soft market conditions at the end of 2012, and the impact on timing and recognition of service revenue and opportunities in our On-Road Systems business," Westport chief executive David Demers said.
"We are expecting a step change in growth over the course of this year and remain confident the market for natural gas as a fuel in trucking is here and now — not five or ten years down the road."
The company said product revenue fell to $27.3 million for the quarter, down from $35.3 million a year ago, due to the timing of a number of major fleet orders and uncertainty around Swedish government incentives which affected the sale of the Westport bi-fuel system for the Volvo V70 cars.
Parts revenue for the quarter was $1.3 million, up from $700,000 a year ago, while service and other revenue was $1.4 million for the quarter compared with no revenue a year ago.
The company's Cummins Westport Inc. joint venture shipped 1,313 engines in the quarter down from 1,943 a year ago, while revenue fell to $44.7 million from $52.7 million.
Weichai Westport Inc., the company's Chinese joint venture, shipped 8,529 units in the quarter, up from 2,728 a year ago. Revenue grew to $105.9 million, up from $37.2 million.
Westport develops engines that use fuels such as compressed natural gas, liquefied natural gas, hydrogen and renewable natural gas fuels such as landfill gas.