The rating of the fuel pump is determined after testing to rate its flow, pressure as well as voltage requirements that it needs so that pumps capabilities can be deduced making them efficient. Measured in either gallons per hours (GPH) or liters per hour (LPH), flow rate is the amount fuel a pump can deliver to an engine for consumption over the time frame of 1 minute. For example, a performance fuel pump can be designed for 255 LPH in order to support the larger needs of a turbocharged engine; which requires far more fuel than is needed by most factory applications. Even a 10 LPH deviation in the rating can hurt engine performance and fuel economy.
Pressure Ratings – This refers to the maximum pressure that can be maintained in a fuel line, which is usually measured in pounds per square inch (PSI). Standard fuel pumps run between 40-60 PSI, and a performance pump may go up to around 100 PSI. Such pressure provides uniform fuel supply, this being especially useful in modern high performance engines functioning at wide range of load. Engine misfires or loss of acceleration can result if the pressure rating is not met.
The majority of standard pumps are 12-volt, but you should always check to see if your voltage is compatible with the pump rating. Tested at various voltages, the power plug pump is to be able to work in a heat state. Low voltage can reduce fuel flow by as much as 20 percent and will detract from overall engine performance. Both Bosch and Walbro, for example, put fuel pumps through water stands that subject the parts to a range of voltage and load conditions to create ratings that should be consistent along with accurate.
Co-founder of Rolls-Royce, Henry Royce used to say strive for perfection in everything. The same principle extends to figuring fuel pump ratings, since accurate readings allow users to match their vehicle with the right pump. A Fuel Pump must have adequate flow, pressure and voltage to ensure nothing is burnt out on your engine when forced in.