McLaren forced to ‘strip down’ MCL40 to chase fuel fault

After Lando Norris debuted McLaren’s new car on Wednesday in Barcelona, the baton was passed to Oscar Piastri, but the Australian's first taste of the new era was cut short by a stubborn ghost in the machine.

What began as a promising morning of data gathering ended with the MCL40 being dismantled behind closed doors. By noon, Piastri had 48 laps under his belt, but he would not turn another wheel for the rest of the day as engineers worked frantically to diagnose a critical failure.

The culprit was eventually identified as a fuel system malfunction, but in the hyper-complex landscape of the 2026 regulations, there is no such thing as a "quick fix."

Stripping Down the Complexity

Mark Temple, McLaren’s technical director for performance, explained that the team had to take the drastic step of completely deconstructing the car to ensure the root cause was found.

“We've got a good understanding of where the car is from a baseline point of view,” Temple noted, striking a balance between optimism and the reality of the setback.

“But obviously we've had some issues. We've not been able to do all the running that we would like. We discovered a fuel system problem.

“The car is very complex, so we decided to bring it back into the garage, strip it down, and fully understand where the problem is coming from.”

Despite the lost afternoon, the team is maintaining the perspective that these hurdles are a feature, not a bug, of testing a revolutionary new platform.

For Piastri, the limited mileage was still an essential introduction to a vastly different driving experience.

“There’s a lot of challenges this year up and down the grid, so it was good to get stuck in," commented the Aussie. "We had a fuel system issue, which cut our day short, but the team’s working hard to get that fixed and back out tomorrow.”

Adapting to a New Formula

With performance taking a backseat to system integration this week, the focus remains on the driver’s synergy with the new power unit and energy recovery systems.

Temple emphasized that while the lap count was lower than hoped, the qualitative data gained by Piastri was significant.

“The most important thing for the drivers this year is to understand how the new car operates, how the power unit interacts, the energy management, all of those things,” the McLaren engineer explained.

“He's got some good references for that. He's also got a feel for how the chassis behaves.”

Piastri echoed this sentiment, noting that the learning curve for the 2026 machinery is steep for everyone involved.

“These cars are completely different to what we’ve had the last few years. That’s part of what this test is about," the Australian remarked.

“We’ve already identified a few things that we can try to improve on the car to make it feel a bit nicer.

Read also:

• ‘It still looks crazy’: Norris reacts to running No.1 on his McLaren

“We have one more day of running tomorrow. We’ll continue to get used to the car and get a good read on how different things feel. Then we’ll find a good direction to make the car quicker and feel nicer.”

With one final day of testing remaining in Barcelona, the Woking-based squad is betting that a total teardown today will prevent a total breakdown when the lights go out in Melbourne.

Keep up to date with all the F1 news via X and Facebook