Power down when I fill fuel!!

Hi Guys

I have another problem with my S13. Car runs very well when on or close to reserve. When I fill up, serious drop in power. Cars struggles to rev. I have replaced fuel pump and regulator but no difference. Fuel pressure is correct.Also bypassed hot start. Changed fuel filter. Any ideas??

Hi Richard H

Im not sure but i will check if the breather pipes and the flow-back pipe to the tank isnt block. Good luck.