Location of the fuel pump is very important for both performance as well as longevity of the fuel system. While most vehicles with modern designs use in-tank fuel pumps which can be fully submerged within the reservoir, there are also external or in-line fuel pumps which are prefered with some older models and performance exceed vehicles. Because in-tank fuel pumps are submerged in the fuel, they benefit from natural cooling and are much less likely to overheat. If left submerged, they operate at a more even temperature so long as kitted up and will provide better life expectancy of around 100-150k miles. Its immersion also reduces the likelihood of the fuel boiling off in the lines—known as vapor lock, a phenomenon that occurs when it gets so hot the fuel vaporizes and clogs the lines.
External fuel pumps, on the other hand — like the Bosch 044 or Aeromotive electronic unit I used to run myself — are mounted out in the breeze, where they can’t help but heat-soak up more of Mother Nature’s peaceful rage associated with hot engine-bay temperatures right alongside possibly even hotter ambient ones at times. However, electric pumps are generally more prone to temperature spikes without the cooling effect of the fuel and as such suffer from a decreased efficiency over time, possibly 10% to 15% lower than at assembly due to heat driven wear. However, external pumps offer more convenient serviceability and are the way to go for high-end applications where you might have to make regular adjustments.
The placement of the fuel pump can also affect how well pressure is held. Does Your Fuel System Deliver? The advantage of in-tank pumps is that they push fuel a short distance to the injectors with more consistent and higher pressure control (usually regulated 40-60 psi in a fuel-injected engine); The close spacing helps to ensure a constant, uninterrupted discharge that can be very important in avoiding pressure loss levels that could affect engine power and fuel efficiency. External pumps are also used, and while they have their advantages for higher-level performance tuning, may need extra regulators or lines to maintain the same level of pressure consistency like those utilizing just a Boost-a-Pump, which will complicate the fuel system setup and drive up the cost too.
Ford himself put it well when he said “Quality means doing it right when no one is looking,” emphasizing the value in selecting the correct Fuel Pump location for your vehicle and its specific needs. The proper pump location becomes the building block choice for efficient fuel system performance, contributing to improved reliability, optimal cooling and pressure control.