A number of important specifications come into play in the selection of a fuel pump relay for compatibility and proper performance. The voltage and current rating of the relay is important. Most fuel pump relays are rated at 12 volts to match the rating of standard automotive systems, while the current rating is generally in the range of 15-20 amps. Such high-performance applications, like in turbocharged engines, may also require higher current-capacity relays that are able to cope with increased electrical demands, since overheating and possible premature failure might be prevented. A relay selection rated a little higher than what the fuel pump requires, amperagewise by around 20%, will ensure longevity and reliable performance.
There is, for example, the type of relay used, be it electromagnetic or solid-state. Electromagnetic relays have been in widespread use in most vehicles and employ mechanical contacts to switch the circuit on/off, handling the requirements of the fuel pump in a standard manner. In contrast, solid-state relays use semiconductor materials without mechanical parts and thus boast better durability and the ability to handle higher current loads with much more smoothness. They are especially helpful in high-demand vehicles since they eliminate the possibility of contact wear over time and also reduce the possibility of failure in a relay. Solid-state relays cost a bit more; however, their lifespan tends to be longer, and they are highly recommended for high mileage or performance vehicles.
Selection of a relay also involves determining the heat resistance; some applications show under-hood temperatures upwards of 200°F (93°C). Relays with high-temperature ratings and robust casings prevent thermal stress, especially in high-performance or heavy-duty vehicles. Relays placed in closer proximity to the engine should meet higher standards to avoid failure due to heat exposure.
Of equal importance, specifically for vehicles exposed to harsh conditions such as driving in winter and along salted roads, is the selection of relays whose contacts are resistant to corrosion. Moreover, these materials provide better electrical conductivity and, at the same time, avoid problems later on due to corrosion. This will be particularly useful in areas of very high humidity or frequent rain, where normal contacts could deteriorate faster and result in inconsistent fuel delivery.
Quality, in the words of Henry Ford, is “Doing it right when no one is looking.” Selection of a high-quality Fuel Pump relay that is applicable for the subject vehicle and for its intended operation helps prevent electrical issues and assist in maximizing the life expectancy of the fuel system. See also Fuel Pump for additional information on proper selection of a fuel pump relay.