It's been a while since I last worked on fuel pump but if I remember correctly it is as marked up in pictures below. Stage 1 output from the pump takes fuel from baffle housing and deliver fuel to suction jet pumps which pick up fuel from lower parts of fuel tank and dump it in baffle housing, stage 2 takes fuel from baffle housing and delivers it to the engine. So if the the engine was working for the while there was fuel in the baffle housing but it stopped working because it ran out of fuel in baffle housing. It could be because stage 1 output from the pump is not working or if the fuel from stage 1 output was not going to the fuel jet pumps. Maybe there was just not enough fuel to get the fuel jet pumps working properly before it ran out. If you put some fuel in the tank it goes straight in the baffle housing so garage can put small amount in like 0.5-1l in the tank and see if it will work and keep working after that amount is used.
There is o-ring where the pipes join for stage 1 circuit, I guess it might have gone but don't see why.
