Full Flow

Installing Fleece Performance Engineering’s PowerFlo In-Tank Lift Pump

This ’12 Ram will be graced with one of Fleece’s cutting-edge products: its PowerFlo in-tank lift pump module. Designed as a direct replacement for the factory sending unit assembly—and with the goal of supporting higher horsepower while maintaining quiet, air-free operation—the PowerFlo lift pump is ground-breaking on multiple levels.

From a reliability standpoint, the pump’s active fill technology keeps air from ever infiltrating the fuel system. From an operational standpoint, its in-tank design makes it less audible than external (chassis-mounted) lift pumps. From a performance standpoint, the system employs two proven, OEM-style gerotor pumps, which provide a combined flow of nearly 170 gph at rated pressure—enough to support 800-rwhp. And from an installation standpoint, there are no holes to drill in the tank, no fuel lines to run, and no wires to splice. The install is as easy as it gets.

While the factory lift pump on our ’12 6.7L Cummins was keeping up with the stock injectors and CP3 just fine (despite us running aftermarket tuning aggressive enough to kill the 68RFE transmission), we have a goal of eventually matching the recently-installed S467 with a set of 100-percent over injectors and a stroker CP3. So, there was no time like the present to lay the groundwork for our future, 750-rwhp endeavor by installing Fleece’s PowerFlo lift pump. After less than three hours of labor, the PowerFlo unit was in place and the truck’s low-pressure fuel system had effectively been prepped for its pending injection system upgrades.

Fleece Performance Engineering’s PowerFlo in-tank lift pump is a fully self-contained assembly that directly replaces the factory sending unit. The lift pump module comes with a plug-and-play wire harness, a float arm, and a sending unit O-ring. As we went to press, the PowerFlo lift pump was solely available for ’05-newer Cummins applications, but Fleece had plans to offer Duramax and Power Stroke versions at a later date.
Thanks to utilizing two OEM style gerotor pumps, the PowerFlo lift pump flows 168-gph at 15 psi, which is comparable to the popular, 165-gph externally mounted fuel supply systems in the aftermarket. This kind of flow makes the PowerFlo lift pump capable of supporting dual CP3’s. On the durability side of the equation, each gerotor pump has been proven to last more than 12,000 hours (more than 300,000 miles).
To stamp out any over-pressure possibilities, an internal pressure regulator is integrated into the head of the tank flange. The internal pressure regulator also ensures proper fuel pressure always makes it to the CP3(s). Each PowerFlo assembly comes with the appropriate fittings required to seamlessly attach your factory quick-connect fuel lines. Also notice the supply-to-engine arrow (left) and the return-to-tank arrow.
What makes the PowerFlo unit truly unique is its active fill bucket, which perpetually scavenges fuel from the bottom of the tank and, as a result, is always full of fuel. This means that air never has the chance to infiltrate the fuel system (eliminating the need to run an air separation system). And because the bucket is always full of fuel, there is no need to run a tank sump or a draw straw. The quarter-tank problems associated with aftermarket fuel systems is a non-issue with the PowerFlo lift pump.
Here you can see the fill bucket venturi that—by utilizing a small amount of flow from the gerotor pump next to it—keeps the gerotor pumps completely submerged at all times and (once again) eliminates those pesky quarter-tank issues commonly experienced with draw straws, or the air-suction issues associated with sumps. Also notice the passive fill diaphragms on the bottom of the bucket (one for each gerotor pump).
As yet another means of insuring the fill bucket is constantly being flooded with fuel, even the diesel that’s returning to the tank passes through the fill bucket first. The return line is the clear hose shown here, to the left of the two supply lines feeding the head flange.
The hardest part of wiring up the PowerFlo lift pump involves mounting the relay. Other than that, it simply piggybacks in with the factory wire harness, requiring zero cutting or splicing. To guarantee ample voltage makes it to the PowerFlo system, 12-gauge wire is used (along with a 20-amp fuse).
Knowing the job entailed tight working quarters on top of the tank (for disconnecting the various factory lines before the tank could be dropped), we gave ourselves a little breathing room next to the fuel tank by removing the rear drive shaft. Then the factory heat shield between the fuel tank and exhaust system was pulled, followed by the filler neck being disconnected from the tank.
With a transmission jack in position under the fuel tank, the tank itself strapped to the transmission jack, and both tank straps removed, we lowered the tank just enough to access the top of the factory sending unit. Then the tank’s vent tube, wire harness connector, and supply and return lines were disconnected.
Installation calls for either dropping the factory tank or pulling the truck’s bed to gain access to the top of the sending unit. Due to having a two-post lift at our disposal and it also being our preference, we chose to drop the tank.
From there, the tank was lowered out from underneath the truck and wheeled into a well-lit area. Full disclosure: we made sure to run the truck down to an eighth of a tank of fuel prior to the install. In a job like this, the last thing you want to do is fight a full fuel tank, with 30 gallons sloshing back and forth.
Prior to attempting to break the sending unit’s locking ring free, we cleaned all debris off of the top of the tank. After dousing everything is brake cleaner, we followed it with compressed air. You definitely don’t want any contaminants to make it into the fuel tank while you’re performing the sending unit swap.
Before the factory sending unit was pulled, and as per Fleece’s instructions, we took note of the tank flange tab’s location. The tank flange tab on the PowerFlo assembly would have to be lined up in the same manner when it was installed. Immediately after lifting the factory sending unit out of the tank, as much excess fuel as possible was carefully poured back in.
To get the locking ring loose, a flat head screwdriver and hammer were employed to turn it counter clockwise. Once removed, we treated the locking ring to a thorough cleaning as it would be reused with the PowerFlo lift pump assembly.
Positioned beside the factory sending unit, you can see that the PowerFlo lift pump is virtually a dimensional replica other than its head flange. We’ll also note that the supplied level sender/float assembly is properly scaled to keep your fuel gauge reading 100-percent accurately.
Just as it was on the factory sending unit, the PowerFlo lift pump’s supply port feeding the CP3 measures 3/8-inches. However, for customers that’ve already installed larger diameter lines than factory, these quick-connect fittings can easily be swapped out for AN fittings.
With the supplied sending unit O-ring in place and the new float arm installed on the PowerFlo lift pump, the entire assembly was lowered into the tank. While dropping the new sending unit into place, we took special care that the tank flange tab’s orientation was the same as the factory one had been.
The original locking ring can only be installed one way over the head of the PowerFlo sending unit, and it was tightened up the same way it’d been broken free earlier: with a long flat head screwdriver and a hammer. On top of quiet operation, another benefit of sticking with an in-tank lift pump is that it’s much less susceptible to gelling up in winter weather than external fuel supply systems are.
Next, we plugged the male end of the PowerFlo lift pump connector into the factory wire harness while allowing the female connector to hang until we could reinstall the fuel tank. Because it would be hard to secure the wire harness with the tank in the way, the supplied 12-gauge wire harness was anchored along the frame rail via zip ties before the tank was reinstalled.
With the fuel tank hoisted up, near its final position via the transmission jack, the female connector on the PowerFlo lift pump’s wire harness was plugged in and the factory quick-connect fuel supply and return lines were attached. Then, with everything connected on the top of the tank, it was raised up, the tank straps were reinstalled, and the transmission jack was removed.
Now that the fuel tank was back in place, the rear driveshaft could be reinstalled. But before sending each bolt home with our electric impact we treated each fastener’s threads to Loctite.
In order to ensure consistent voltage always makes it to the PowerFlo lift pump, Fleece supplies a dedicated fuel pump relay. After routing the wiring up into the engine bay, we decided to mount the relay inconspicuously along the firewall using a self-tapping screw.
To keep things looking as neat and clean as possible in the engine compartment, we opted to route the extra wire in the harness back down along the frame. The excess wire would end up looking like this: looped (not wadded up) and zip-tied to the truck’s existing fuel line (left).
From there, the only thing left to do was attach power and ground to the positive and negative battery terminals and cycle the ignition. Right away, we noticed how quiet the PowerFlo lift pump operates—and with the engine running you have no idea it’s even been added to the truck. Saying this system is revolutionary might be an understatement. You get factory packaging, noiselessness, and pump reliability, but with enough flow to support more than 800-rwhp. If ever there was a sleeper of the low-pressure fuel supply world, the PowerFlo in-tank lift pump would be it.


Fleece Performance Engineering

You May Also Like