as an old guy I have seen this. IF no one has treated the fuel for some time it can and will grow bacteria in the tank till it plugs the system. symptoms are... no acceleration and hard starts. I have seen it so bad the tank looked like it was full of black jello. had to have the tank flushed out and blow out the lines to the pumps. its usually worst in cold temps as it makes the fuel hard to draw and it cavitates the injection pump and lift pump.