"Nico
Extract of the logs:
03/09 19:32:56 On lap 20 at 0.658859, M Maurício (Driver:8220) set to make pitstop 2 by Order.
03/09 19:33:22 M Maurício (Driver:8220) enters pitlane on lap: 20
03/09 19:33:33 M Maurício (Driver:8220) completes Lap 20 at Race Time:2013.169497s with: FuelLitres:22.319 TyreCnd:0.42355 TyreTmp:92.4071 Compd:1
03/09 19:33:36 M Maurício (Driver:8220) arrives at garage and stops.
03/09 19:33:36 M Maurício (Driver:8220) is filling to the amount specified in the next stop row: 22L.
03/09 19:33:36 M Maurício (Driver:8220) is not changing the tyre strategy because this is an ordered unscheduled stop.
03/09 19:33:36 M Maurício (Driver:8220) makes pitstop 2
03/09 19:33:36 M Maurício (Driver:8220) refits compound 1
03/09 19:33:41 M Maurício (Driver:8220) completes pitstop and leaves the garage.
03/09 19:33:57 M Maurício (Driver:8220) leaves pitlane on lap: 21
03/09 19:35:27 M Maurício (Driver:8220) completes Lap 21 at Race Time:2126.855247s with: FuelLitres:18.8623 TyreCnd:0.914761 TyreTmp:69.5226 Compd:1
You manually clicked on the pit button therefore your driver pitted. He didn't get enough fuel to finish the race so he had to pit again.
thats just the case. i set it up to 39 liters, in 2D it says it has 39 liters!