Volvo: 87 Volvo losses fuel/power under load

Question
Hi Robert
Right now I'm driving my car around with the gas cap off. I had been driving down the highway a hit the gas for passing gear - nothing - I had to limp over to the side of the road.

My in-tank fuel pump has been out for quite a while - I keep it at more than have full. I can still drive it - even on the highway - very carefully. Been like this for a week now

Thanks,
Mark

Answer
you did not say if this is a turbo or not .The prepump helps with delivery seeing that the main pump is so far away from the tank .So i would get that fixed ,as for the lack of power does it buck or surge when this happens or just has no power ,does it stall. There may be a mass air flow issue but i will need a little more info even if you keep the tank past 1/2 full the prepump needs to deliver to the main pump ,hope this helps ..