Welcome to the
Home of the Vegistroke

Known OEM #8 Injector starvation issues and how DFA addressed and fixed it - Detailed

The 7.3 Powerstroke Diesel (PSD) is one of International's best motor's ever, However there are a few quirks with the High pressure oil and the fuel system that wound up causing injector starvation in the #8 injector. Both the High Pressure oil and the fuel starvation are caused by the same issue, but High pressure Oil is another discussion altogether. The type of fuel system they use is commonly called a deadhead system, which means there is no return from the fuel rails. Fuel goes in, but not out. Pressure is regulated to 60-75 psi at the OEM fuel bowl. The cylinders are labeled  right to left, meaning the on the Passenger side you have 1,3,5 and 7 front to back. On the Drivers side you have 2,4,6 and 8 front to back as shown in Figure 1 below. Looks simple enough, However the fuel rails are actually a cast in passage in the head. And only hold about 1.5 ounces of fuel, so not much volume to support such a large motor. Now take into account the firing order of 1-2-7-3-4-5-6-8. Since the fuel feeds only from the front of the rail on that side, and 6 fires immediately prior to 8 there is simply not enough volume or time for the pressure to recover prior to 8 firing. So at say 2000 rpm each injector is firing 12.5 times/second!! Or between the 2 of them, 25 firings/second. With no other source for fuel, The small passage can not recover the pressure in time to supply 8 with proper fuel pressure and filling. Result- Noisy injector and slight power loss.

Okay, so how did Ford fix it? By creating a "Long Lead" injector to put in #8 which was supposed to give the injector a longer pre-injection event in an attempt to quiet cackling. All that did was ruin the timing ability of the injector and not fix the problem at all.

The standard aftermarket fix is to install a regulated return type fuel system as shown in Figure 2 below. In this case the pressure is regulated after all the injectors and you have added effectively more volume to the fuel rails, so a more consistent pressure is maintained. However, even this way has it's limits. The regulated return is still only feeding fuel to 2 1/8npt ports which are the limiting factor the PSD's fuel system, and no one seems to address this. But then it is only an issue at high power levels. Believe it or not, there is yet a third way to maintain an even pressure. And that is the Vegistroke way!!

Ok, so what is the patent pending Vegistroke way that is so different from every other approach?  Well it is a double deadhead crossover design as illustrated in Figure 3 below. Here I have pretty much left the factory system alone except for adding a check valve to the stock fuel ports (no cutting required) at the heads, and tapped into the two previously unused fuel ports at the opposite ends of the heads. And while the system has gone through a few evolutionary changes, the premise is the same, fuel switching is based on temperature, and pressure. After utilizing those fuel ports, the lines are T'd together creating a crossover balancing effect for the fuel rails while on diesel. Injectors 1 and 8 are no longer the end of the line and fuel can feed from both ends of the rail. Many have done a crossover with the High pressure oil side of the injectors to balance out the spikes and valleys and help fix the other part of the cackle issue mentioned earlier.  So now in the Vegistroke system, once the engine has come up to proper operating temperature, The WVO pump is turned on. Once the pump comes on, if all is right, then the system builds pressure, and eventually trips a custom pressure switch which then shuts off the stock diesel pump and without pressure in the diesel system, the check valves on the diesel side close, system light comes on, and the truck runs on oil. Should anything ever happen to cause the WVO pressure to fall below 60 psi, the diesel pump comes back on, and you will never notice a thing, other than the light on the system switch extinguishing. Combined with the 100% automatic shutdown system (with manual backup) and you have a piece of mind that no other kit can offer.

Food for thought for you extreme power junkies out there. So what happens if are running so much power that  the stock diesel system, or even (highly unlikely) that the Vegistroke fuel system can not keep up? Well once the pressure drops below a given point, (well above any noticeable power loss) the diesel system kicks back on, and you now have TWO complete fuel systems feeding all 4 ports on the heads!! There is no other performance system on the market that can lay claim to that. And I still have the ability to purge any trapped air from the system as well.

FIGURE 1

FIGURE 2

FIGURE 3

Dino Fuel Alternatives Technical Bulletins are available for download in .pdf format.  You will need to have Adobe Reader installed in order to view or print these documents.  Click on the Adobe Reader image below to download the most recent version of Adobe Reader for FREE from the Adobe website.