ITP DIESEL FUEL SYSTEM WITH AIRDOG
With our cosmetic mods all done, it's time to get back into a performance state of mind. The next step to better efficiency and horsepower in our 7.3L is the fuel system. The new Stage II Hypermax injectors outflow the stock injectors by quite a bit and while the factory fuel system is adequate for a fairly stock truck, we're pushing it to the limit now. Our in-cab Autometer fuel pressure gauge was showing a significant fluctuation under normal driving conditions and big pressure drops under hard acceleration, it was obvious the factory fuel supply needed some attention.
There are two main goals behind fuel system modifications, increasing flow and eliminating air. Recent testing by Alliant Power (a significant player in the 7.3L and 6.0L Power Stroke injector market) showed that the leading cause of injector failure comes from fuel interruption and air in fuel. Meaning, air being passed through the internals of an injector can cause pretty serious harm to the injector itself. While they may seem to run correctly, the injectors will run much smoother and efficiently if that air is removed from the system completely.
The first step will be improving the fuel system on top of the engine, between the heads and the factory fuel filter bowl. The factory system on the 7.3L Power Stroke is a "dead head" design, meaning fuel enters one end of each head and then dead ends at the other. To get there, the fuel must pass through the "kinky" factory fuel lines and restrictive check valves. Once in the heads, the fuel is subjected to heat, vibration and injector spit-back until the injectors finally use it.
To solve this issue ITP Diesel of Glendale, AZ, has designed a Regulated Return system that will allow the fuel to flow "through" the heads and out the opposite end to a high quality FueLab regulator that mounts in the engine bay. This allows the end user to fine tune fuel pressure to the desired level (most 7.3L's will work best with fuel pressure between 58-68psi). Included in the kit are all of the fittings, pre-bent hard stainless steel lines, braided stainless hoses, and the machined fittings needed to complete the installation.
Installing the kit is fairly straightforward, however, it can be rather time consuming. The factory check valves and fuel rail plugs in the heads can be a bit stubborn to remove. Trust us when we tell you, you may find yourself cussing the factory fittings in the backside of the passenger head. There isn't a whole lot of room for your hands and tools back there, but it is possible, just be patient and take your time. This is a job that can be done on a Saturday in the garage, basic hand tools and some time is all that is really needed. ITP Diesel supplies great instructions with the kit, they are very thorough and go through the entire process step-by-step.
By removing the factory plugs in the ends of the heads, the ITP Diesel kit now supplies fuel from the filter bowl into the front of both heads. It then travels through the heads past each injector and exits the backside of the heads. Running from there it flows through the new FueLab regulator and is sent back to the tank. Not only does the kit eliminate the `dead-heading' of fuel in the heads, the new lines are also much larger than the factory hard lines. This will remove some restriction and help improve overall flow to the injectors.