We've heard about several instances of high-horsepower cars with mondo fuel pumps experiencing fuel pump lockup when subjected to several hours of low-speed driving. Some of the causes stem from things like restrictions in the suction side of the pump circuit, high-mounted pumps that require electrical power to draw fuel, restrictive paper filters on the inlet side, low voltage supply or poor grounds to the pump, a restrictive vent system, and/or a high-temperature heat source like exhaust too close to the pump. Under extended driving, especially at low speeds, these various issues or a combination of all of them will heat the fuel and eventually cause the fuel pump to quit due to excessive heat. This can also be partially attributable to small fuel tanks that at º-tank are circulating the fuel very quickly. The solution is to pay close attention to alleviate all the above issues. One solution that does not work is to reduce the voltage supply to the electric pump since that causes the motor to generate more heat and will eventually cause a failure.