The fuel cooler cools the fuel returning to the tank! You want the fuel warm for most efficient engine running.
The hotter it is, the less energy it takes to start burning. Hence the fuel heaters on diesels, older style runs fuel by the coolant, newer ones have an electric fuel heater.
The hotter it is, the less energy it takes to start burning. Hence the fuel heaters on diesels, older style runs fuel by the coolant, newer ones have an electric fuel heater.