Super Aguri pulled out of a test in Spain on Monday, adding to concern about the team's financial health less than a month before Formula One's Australian season-opener.
"Super Aguri F1 team will not be participating at the test in Barcelona this week due to circumstances beyond our control," team principal Aguri Suzuki said in a statement.
"We are planning to attend the test at the Circuit de Catalunya next week with two cars."
Super Aguri are in talks with various would-be investors, including India's Spice Group, after limping through to the end of last season with the smallest budget in the sport.
They had planned to launch their 2008 car in Barcelona on Tuesday but postponed that last week, scheduling instead a question and answer session with Suzuki and technical director Mark Preston.
That has now also been cancelled and next week's official test at the Circuit de Catalunya will be their last before the cars have to be flown to Melbourne for the March 16 race.
The team, who finished ninth overall in 2007, have yet to confirm their driver line-up although Britain's Anthony Davidson is expected to be retained alongside Japan's Takuma Sato.
The new car passed its mandatory FIA crash test this month but Sato and Davidson have taken part in just one test since December.
"I think it's going to be tough, with where the team are at the moment," Davidson told the Autosport Web site when asked about Aguri's prospects for the season.
"It will be hard work for us. We are going to be one of the tail-end cars, for sure."