McLaren has made a number of peripheral changes to Lando Norris' Mercedes power unit in an effort to eradicate a persistent fuel system problem. The team was significantly off the pace on Baku's long straights compared to Mercedes, with which it shares engines. While part of the deficit came from car weaknesses and how the team ran the Mercedes unit, Norris' car was notably down on top speed in qualifying due to a fuel injection issue that McLaren identified.
The problem returned intermittently in the race, also affecting Oscar Piastri's car to a lesser extent, and hampered the team again at the Bahrain Grand Prix in Malaysia. It is understood McLaren has decided to change several auxiliary power unit components, including the fuel system, which sits on the team side rather than with Mercedes, ahead of Singapore FP1.
Norris said he was hopeful but needed to get on track first. "It's been a frustrating two weekends trying to figure out what the issue has been and why there's just been a constant lack of straight-line speed," he said. "So, it's cost me quite a lot." Singapore is one of the least power-sensitive circuits on the calendar, but with a close battle expected among the top four, McLaren cannot afford to leave performance on the table.
More broadly, Singapore is an important test of whether McLaren's weak performance in Malaysia was a one-off. The Sepang circuit was expected to suit the MCL40, yet McLaren was only the fourth-fastest team there, possibly linked to how the car's aerodynamics interacted with the rough track surface.
Source: Autosport F1 News · Summarized by HeadlinesBriefing