Because the peculiar properties of each fuel type vary, the construction in fuel pumps for gasoline and diesel engines differs. Gasoline fuel pumps are typically designed to pump fuel in pressure ranges between 35 and 65 PSI-a pressure high enough to inject fuel in most cars. Diesel engines, on the other hand, require much greater pressures often exceeding 15,000 PSI in common rail systems. This discrepancy in compression ratio is due to the fact that diesel fuel requires higher compression for proper atomization and efficient combustion since it is more viscous and less volatile compared to gasoline.
A Fuel Pump rated for gasoline applications used in a diesel application will surely perform poorly and might damage the engine. Diesel fuel pumps are of stronger materials, heat-resistant, designed to take high-pressure levels, and heavier fuel density. In fact, using an only gasoline-rated pump on a diesel engine would not provide the pressure required, which could lead to poor fuel delivery, engine knock, and even fuel pump failure in worst cases.
Fuel pumps suitable for diesel also have materials and seals that withstand the lubricative but normally corrosive nature of diesel. Because gasoline is lighter and less corrosive, the pumps in gasoline do not have the heavy-duty seals and parts that diesel pumps do. According to Bosch, diesel fuel pumps are designed with heavier-duty components to withstand wear and abrasion, given that the diesel fuel can corrode the typical materials of the pump in due time, which might shorten the service life by 20 to 30 percent when not matched properly.
Cost is also a factor in pump compatibility. Diesel fuel pumps tend to be more expensive, with most falling in the range of $500 to $1000 due to additional robustness and higher pressure. Using a gasoline fuel pump for diesel purposes also does not meet such high pressures, and this may end up wearing down the pump much earlier than it ought to, turning out an inefficient and costly choice in long-term service.
Performance and durability are possible by appropriate choice of fuel pump for the particular type of fuel: changing to a diesel-rated fuel pump in case of using diesel fuel, or keeping the gasoline-rated for gasoline.