The Silverstone-based team have completed far less mileage than rivals, turning up late for an initial shakedown in Barcelona and then struggling with reliability in the two Bahrain tests.
Engine partner Honda said in a statement that a battery-related issue had impacted Fernando Alonso's stint in the Adrian Newey-designed car on Thursday.
"Since then, we have been carrying out simulations on the test bench in HRC (Honda Racing Corporation) Sakura. Due to this and a shortage of power unit parts, we have adapted today's (Friday's) run plan to be very limited and consist only of short stints."
Canadian Lance Stroll, who was due to be in the car all day and whose father Lawrence controls the team, appeared on track for an installation lap just before the lunchtime break but failed to set a time. That compared to Ferrari's Charles Leclerc, who was fastest, doing 80 laps.
"We are not where we wanted to be. We have not done many laps but we have an enormous amount of data for Australia," team director Pedro de la Rosa told Sky Sports television.
Alonso told reporters on Thursday that he had no doubt about Newey's abilities.
"We need to unlock more performance," said the double world champion. "We're still going step-by-step into the car. We are a little bit on the back foot, we have to admit that, but hopefully there is time to improve.
"On the chassis, there is no doubt, we have the best with us. After 30-plus years of Adrian Newey dominating the sport, I think no one will doubt that we will find a way to have the best car eventually," added the Spaniard.
"On the power unit, we need to wait and see when we unlock all the performance, where we are and what is missing, and then work hard."
Luxury sportscar maker Aston Martin earlier suffered a more than 4% drop in its share price after warning of a bigger annual loss than the market expected.
The F1 season starts in Australia on March 8.
