Power Driven Predator Lift Pump Check Valve On some trucks, installing a Predator Lift Pump can reveal an underlying "loss of prime" condition. The nearly universal reason this happens is...
On some trucks, installing a Predator Lift Pump can reveal an underlying "loss of prime" condition. The nearly universal reason this happens is a small leak in the return side of the fuel system has developed. Because there's almost no pressure in the return line while the engine is running, they don't normally leak fuel out. However, when the engine is not running, it can allow air into the top of the fuel system. If fuel is allowed to drain back through the system, a loss of prime or hard starting would develop. Because electric pumps self-prime every startup and a factory 12v lift pump has integral check valves, return line leaks can sometimes go unnoticed for years. It may only become apparent when converting from an electric or factory 12v lift pump to an aftermarket mechanical lift pump like the Predator.
While locating and repairing the leak is the proper fix, it can be a very time-consuming process, and sometimes your time is an important consideration. Installing a check valve is a much quicker repair. When placed between the outlet (top) port of the Predator and the AN fitting, the check valve eliminates the possibility of fuel drainback while the engine isn't running.
