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Installing H&S Motorsports’ Low-Pressure Fuel System For The 6.7L Power Stroke

Posted in How To: Engine on October 9, 2017
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Ford’s 6.7L Power Stroke has proven itself as a reliable workhorse engine. Many owners have even compared it to the 7.3L—the initial bearer of the Power Stroke name that was revered for its 500,000-mile durability. However, the 6.7L Power Stroke brings something to the table that the 7.3L never could: the ability to make big horsepower, easily. Thanks to its Bosch high-pressure common-rail fuel system, the piezoelectric injectors employed in the 6.7L are capable of supporting an incredible 650-700 rwhp without modification. Unfortunately, the performance capabilities of the factory turbocharger and both the high- and low-pressure fuel systems don’t allow the full potential of the injectors to be realized.

After replacing the restrictive factory turbo with a higher-flowing fixed-geometry BorgWarner S366 SX-E and adding a second injection pump to the mix, the owner of the ’11 F-250 in this article was well on his way to the 700hp mark—or so he thought. During the initial testdrive, a low fuel pressure warning came across the dash, indicating that the OEM lift pump’s ability to keep up with the demand of the dual injection pumps wasn’t up to snuff. Luckily, H&S Motorsports offers a low-pressure fuel system to address this exact issue. During the course of installing H&S’s comprehensive system, we took note of all the fine details that set this kit apart from other aftermarket offerings. Read on to see why this is the ultimate fuel system for the 6.7L Power Stroke.

The ability to produce 29,000 psi of rail pressure in a relatively small package size makes the Bosch CP4.2 a marvel of modern fuel injection engineering. However, one thing the CP4.2 pump does not tolerate is a lack of low-pressure fuel supply. If adequate supply pressure isn’t maintained, the CP4.2 could check out. And when a CP4.2 calls it quits, it usually does so in catastrophic fashion, effectively eating itself, forcing shrapnel through the injectors, and even returning metal back to the fuel tank. This is why it’s important for you to look at the H&S Motorsports Low-Pressure 6.7L Fuel System as an investment—a performance investment that pays off in the form of you being able to enjoy your extra horsepower for the long term.
From the factory, the 6.7L Power Stroke utilizes an electric lift pump as part of an all-in-one assembly (primary filter, pump, water drain valve) that Ford refers to as the diesel fuel conditioning module (DFCM). The pump supplies the low-pressure inlet of the CP4.2 injection pump with 50-55 psi of fuel pressure. In stock form, the lift pump has no problem keeping up with the CP4.2’s demands. However once a second injection pump has been added, as was the case in this application, the lift pump struggles to keep up. Once low-pressure fuel supply drops below 48 psi, a fuel pressure switch triggers the PCM to de-rate engine power by 30 percent.
Chosen for its 200 gph flow rating, the lift pump supplied in the H&S Motorsports low-pressure fuel system is more than capable of supplying adequate fuel pressure to both injection pumps. Additionally, the highly efficient pump provides quiet operation and comes with a two-year warranty. For ease of serviceability, a popular and highly available AirDog WS100 pre-filter water separator keeps diesel entering the pump free of water and debris. The WS100 retails for $26.
Installation of the H&S system is greatly simplified by reusing the OEM fuel supply line. The factory hard line offers more permanence than any rubber aftermarket material can provide, and its 1/2-inch diameter is sufficient for both stock and performance applications. Retention of the factory supply line also means that the OEM quick-connect fittings are retained. The only fuel hose supplied in the H&S kit is a pre-assembled 1/2-inch section that routes fuel from the tank to the lift pump’s inlet port, and a longer 3/8-inch section that’s used as return line.
Unlike other aftermarket fuel system installs, the wiring process for the H&S system is nearly effortless. The extent of wiring everything up involves scrapping the factory lift pump power supply connector in favor of the unit supplied by H&S (what plugs into the lift pump). The new lift pump pigtail is simply spliced into the factory power supply wire harness and receives a long-lasting, weather-tight seal thanks to the included heat-shrink butt connectors. Just like stock, the lift pump runs at key-on. The truck’s PCM has no idea the factory lift pump has been replaced.
Of a regulated return design, desired fuel supply pressure is set on the return side with the H&S system. An adjustable Fuelab fuel pressure regulator combines with a Fuelab fuel pressure gauge in order to establish the correct supply pressure figure. While the system is infinitely adjustable from 20-100 psi, H&S recommends supply pressure be set between 55 and 60 psi.
Adding further credibility to the quality of the H&S low-pressure fuel system, Grade 8 hardware abounds throughout the kit. The mounting bracketry is made from 1/4-inch-thick, laser cut steel that’s been powdercoated, and everything bolts together along the driver-side framerail (zero drilling is required).
These two CNC-machined, billet-aluminum fuel filter bases facilitate the use of a Baldwin spin-on filter (PN BF7967) on the engine and the aforementioned WS100 water separator mounted in front of the lift pump. A billet filter base is used on the engine in order to accommodate the additional feed line required for supplying fuel to the second injection pump (in single injection pump applications the extra port is simply plugged). The required (and supplied) 3/8-inch fittings allow the OEM fuel lines to seamlessly adapt to the filter bases.
Noise and vibration complaints are common in the aftermarket fuel system realm, so to keep things as hushed as possible H&S supplies rubber grommets in its kits to cut down on any humming or resonance produced by the lift pump. When installed, the grommets are squished to roughly half their original size (pre-loaded) and effectively isolate the fuel pump filter bracket from the frame-mounted bracket.
Here you can see that the fuel pressure regulator has been mounted to an existing stud along the driver side of the firewall, and that all fuel supply and return lines have been attached to the regulator and billet filter base. As far as fuel flow is concerned, the OEM fuel line equipped with the yellow push lock supplies fuel from the lift pump; the line with the green push lock represents the supply line that feeds the factory CP4.2 injection pump; and the 3/8-inch hose spanning from the far side of the filter base to the regulator passes fuel straight through the regulator, and ultimately on to the second injection pump. Although it isn’t visible here, a 3/8-inch section of fuel hose is also attached to the bottom of the regulator, which serves as the return line to the fuel tank.
Reminiscent of where the factory DFCM was positioned, the mounting location of the H&S lift pump assembly keeps it tucked in as close as possible to the inside portion of the driver-side framerail—and out of harm’s way. Its compact overall size makes this system a no-brainer for truck owners that prefer a concealed look, or for anyone that spends any amount of time off-road. Thanks to its tight packaging, top-of-the-line components, improved filtration, and superb fit and finish, this is easily one of the highest quality fuel systems available in the diesel industry.

Justifying the $1,299 Cost of Admission
*200 gph lift pump—this system has no problem supporting well north of 700 hp
*Adjustable fuel pressure regulator and fuel gauge are included
*In CP4.2/CP3 dual injection pump applications, the factory CP4.2 pump sees slightly more supply pressure than the CP3 (just as it should)
*Direct replacement, bolt-in system (no drilling)—consumes roughly the same space as the factory assembly
*You DON’T have to drop the tank in order to install it
*Retains all of the factory fuel supply line (no cutting or splicing is necessary)
*No nest of wires to install—the only electrical work mandates you tap into the factory lift pump’s source for power

Sources

H&S Motorsports
855-623-4450
hs-motorsports.com

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