Fuel Pump Unit - CompleteDelphi Fuel Pump Unit Complete unit with pump Not rare when the fuel pump or the tank unit itself fails, causing fuel pressure drop. The main experience when this happens is misfire or engine stall. In our experience, changing the fuel pump only may not fix the problem as the actual unit fails (age) with the pump. We have tested these units in factory and ported street applications, also in race cars with surprisingly good results hence we recommend