Ford produced some award winning diesel truck designs between 1999 and 2003 that for the most part boasted overall improvements for the Powerstrokes. However, in Ford's attempt to lower fuel tank emissions by preventing fuel heated in the fuel rails from being returned to the fuel tank, they had created an entirely new problem. This is a common problem in Ford Powerstrokes, referred to as "dead-heading", by diesel enthusiasts which gets it's name from the process feeding fuel into the fuel rail head.
Each injector gets its fuel from the fuel rail head, unfortunately, this "rail" has no outlet and ultimately starves the injectors of fuel. The lack of fuel to the injectors causes them to run inefficiently while increasing noise. Fuel held in the rail can also become heated because it is no longer flowing which causes additional injector noise and wear. Ford attempted several fixes but the problem persisted until the 6.0 Powerstroke Diesel Engine was introduced in 2004.
The 1999 to 2003 Ford Diesels were and still remain tremendously popular trucks. This means that there are many people suffering from "dead-head" fuel system problems. These problems can cause poor mileage, loss of power, and noisy operation. Many of the effected trucks can also exhibit a noticeable knock at idle. Engines that exhibit a knocking sound also usually experience a loss of power combined with poor fuel economy. These symptoms are caused by air being drawn into the fuel system and getting trapped there.
Attempting to convert this type of engine to VO in order to solve dead-heading is not really a suitable solution. Because the fuel is dead-headed in the fuel rails, any fuel that remains in the rails must be consumed in order to make room for the incoming fuel that displaces it. So, if you are running on Diesel and wish to switch the engine to VO you must run the engine long enough to consume the fuel in the rails before any VO can be burned. This is actually more of an issue when switching from VO to Diesel because the engine will need to run for 15 minutes or more on Diesel before it can be shut down safely.
The Fuel Rail Crossover or regulated return is a much more suitable solution and was made specifically to solve the 'deadhead' fuel rail issue found in the 99-03 Powerstroke engines. The Fuel Rail Crossover, (FRx), connects the two heads and allows the air to return by another path rather than forcing it through the injectors preventing them to do their job efficiently. This product was designed as a true bolt on system which eliminates hack fixes that require the need to cut the return line and use compression fittings. The FRx is also machined to provide from 72 psi depending on the type of spring used in installation which is perfect for stock parts or upgraded performance parts. This fuel rail crossover system completely eliminates air in the fuel system which in turn provides a smoother ride, quieter idle, less cackle, better throttle response and increased fuel injector life. It also comes in at a fraction of the price when compared to other regulated return systems that do the same thing, making it a no-brainer.