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Clean and Dry Diesel Fuel for Our 2002 Chevy Silverado 2500HD Duramax

AirDog II-4G diesel lift pump install.

Jun 22, 2020

A steady supply of clean and dry fuel is essential to the long and happy life of a diesel engine. From its introduction in 2001 and through the 2010 model year, GM's 6.6L Duramax diesel engines were not equipped with an external diesel fuel lift pump. Instead, they relied only on the scavenging ability of the Bosch CP3 high-pressure fuel injection pump.

In stock form this system worked OK. The CP3 pump was equipped with a scavenge pump and designed for this function. Unfortunately, over time these pumps can wear out, leading to premature wear of the high-pressure pump, along with degraded engine performance from a lack of fuel being supplied to the high-pressure rails and injectors. Fortunately, there's an easy fix for this all too common problem.

Aftermarket diesel fuel lift pumps are cost effective and easy to install. Pureflow AirDog is one of the leaders in the industry and offers lift pumps for most trucks and performance needs. For our 2002 Chevrolet Silverado 2500HD project we opted for the AirDog II-4G pump. These pumps come in four different output ratings, 100 gallons per hour, 165 gph, and 200 gph. The lower output is best for stock trucks, the middle for modified street trucks, and the largest for competition rigs. Since our goal of 700 rear-wheel horsepower is fairly reasonable, we opted for the 165 gph unit.

Photo 2/16   |   Knowing that we'd be installing larger fuel injectors and a bigger CP3 injection pump, among other things, a fuel lift pump was a must-have item. Aside from better filtration, a quality lift pump like the AirDog II-4G ensures that the pump is never starved of fuel.

In addition to supplying a constant volume of fuel to the engine, the AirDog II-4G also works to filter contaminates out of the fuel along with separating both air and water from the fuel. The result is an extremely clean and consistent fuel supply for the engine, even under heavy load.

Installation of the AirDog II-4G took just a few hours with basic hand tools. Even the wiring of the pump is quick and easy. During operation we found that our pump puts out a consistent 14psi of fuel pressure without us needing to adjust the unit. Its operation is also incredibly quiet, with the pump being barely noticeable with the key on and engine off.

Photo 3/16   |   The AirDog II-4G lift pump comes with everything that's needed for a complete installation. There are parts in each kit that are vehicle specific, so be sure you order the correct part for the job.
Photo 4/16   |   For attaching the pump to the truck AirDog provides a bracket that sandwiches the frame rails. This bracket, along with the spacer block, work to place the unit in its traditional home that people are used to seeing. Custom mounts can be found that place the pump under the truck or in more out-of-the-way locations.
Photo 5/16   |   The first step of the installation is attaching the pump mount to the frame mount via the spacer block. A test fit is needed first to determine which position the pump bracket needs to be placed in to best fit the framerail.
Photo 6/16   |   With the pump bracket attached to the mounting bracket, the next step is to bolt the pump housing into place. The pump secures to the bracket with an Allen head bolt and a nut. Be sure not to over-torque these bolts.
Photo 7/16   |   Next, we installed the fuel fittings into the AirDog II-4G pump housing. The larger, -inch male J2044 connectors are torqued to 10 ft-lb (120 in-lb) and go on the ports labeled "Engine" and "Fuel In." The smaller 5/8-inch J2044 fitting is placed in the "Return" port and torqued to 5 ft-lb (60 in-lb).
Photo 8/16   |   With the pump complete and attached to the mounting bracket, the whole assembly can be mounted to the truck's frame. Seen from the back side, the frame sandwich bracket attaches with two bolts at the top and one on the bottom. The pump should be placed along the flat part of the framerail, before it juts upward.
Photo 9/16   |   When mounting the pump unit on the bracket, it is important to install it with the "Fuel In" fitting facing the rear of the truck. This ensures the clearest path for the fuel hose from the tank to the pump and from the pump to the engine.
Photo 10/16   |   The AirDog II-4G install kit comes with 20 feet of fuel hose and all of the needed fittings. We found the most difficult part of the installation to be getting the fresh hose onto the new fittings. It took a lot of patience, lube, and a bit of force to get them all to seat correctly. The fuel feed line from the tank attaches to the sending unit port on top of the tank, while the fuel to the engine can either connect at a rearward fuel line juncture or at the engine. The return from the pump feeds back to a fitting added to the fuel filler neck.

Dorman Stainless Steel Replacement Fuel Lines

As part of our fuel system refresh, we opted to pick up a set of Dorman stainless steel replacement fuel lines from Summit Racing. As always, shipping from Summit was incredibly quick, with the parts arriving at our door the next day. Because the factory lines are, for the most part, a single unit from the engine to the fuel cooler and are difficult (if not impossible) to remove, Dorman ships their replacement set in multiple pieces with flex line to join the parts. Not knowing the condition of our fuel lines made this upgrade a no-brainer in advance of our performance engine build.

It's no small chore to replace the fuel lines, and the process took us the better part of a day. GM didn't do folks any favors when it chose the routing path for the factory fuel supply and return lines. Had they simply run the lines straight down the framerails, the task would be easy. Instead, they bob and weave their way down from the engine, over to the transmission, back to the frame, up, over, and below crossmembers. On our truck we weren't able to take the factory lines out in one piece, so out came the trusty reciprocating saw.

The new Dorman pieces are installed in a pretty straightforward manor, but the lack of directions often left us confused on just which section went where. And we had a bit of a tough time keeping the new flex lines from kinking. In the end, however, we feel it's a very worthwhile upgrade to make, especially for higher-mileage trucks.

The Dorman fuel line kit ships with everything that's needed to install the lines. Even new mounting brackets are included. Our 2002 Chevrolet Silverado 2500HD used a few different kinds of mounts, from push-in to bolt-on, and they were all included.

The factory fuel lines are quite difficult to remove. They run from near the driver side exhaust manifold, along the framerail, through the fuel cooler, and to the tank. The longest section of tubing stretches from the engine to the cooler and required cutting in half to be removed.

Sources:

Pureflow AirDog
www.airdog.com

Summit Racing
www.summitracing.com

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