Don’t Break the Bank: Affordable Duramax Fueling Upgrades
Matt Kutchera’s LLY-equipped 2005 Silverado 2500 LTZ is fully loaded, has ridiculously low mileage and is as clean as they come. Prior to our PPE fuel upgrades, the rig had full exhaust, a cold air intake and a combination of PPE and Edge tuning products.

Matt Kutchera’s LLY-equipped 2005 Silverado 2500 LTZ is fully loaded, has ridiculously low mileage and is as clean as they come. Prior to our PPE fuel upgrades, the rig had full exhaust, a cold air intake and a combination of PPE and Edge tuning products.

As with any diesel engine, more air and more fuel means more power. So naturally, the more fuel trucks receive, the better. However, not long ago, the sentiment that more is better came back to bite some Duramax fans when they realized that nudging horsepower past the 400-hp mark produced diminishing returns, not because the almighty GM mill wasn’t capable, but because it was being choked from fuel for a few simple shortcomings.

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“In stock form, the truck had 2.5psi of vacuum, but with the pump in place we had 8psi of positive pressure—how’s that for big gains?”

Again, this isn’t to say that the Duramax is an improperly designed motor, because they really are great performers out of the box. But as soon as diesel enthusiasts started wicking them up, it was immediately apparent that the factory fuel feed lines, pressure relief valve and CP3 just couldn’t handle the load of a heavily juiced-up tuner.

Thankfully, Pacific Performance Engineering (PPE) engineered some affordable fueling upgrades that do wonders for modified trucks. This isn’t to say they’re not worthwhile modifications on a stock truck, but the return on investment will be much larger with a truck already outfitted with a tuner, intake and exhaust upgrades that are already asking too much of the factory fuel system.

Take for example, Matt Kutchera and his LLY-equipped 2005 Chevrolet Silverado 2500 that was previously modified with a mild lift, upgraded rims and go-fast bolt-ons like a cold air intake, full exhaust and a combination of PPE and Edge tuning components. The truck was a great performer, but when loaded with his toy hauler, the truck would run out of steam on the steepest of hills.

A quick call to the Duramax gurus at PPE unearthed some simple and affordable fueling mods that were aimed at not only increasing fuel pressure, but also maintaining it under long, heavy-throttle pulls where the stock system simply runs out of fuel. With the powerful but effective fueling mods in hand, we paid a visit to the diesel specialists at Left Coast Diesel in Livermore, California, where master tech Ethan Barker not only installed the trio of PPE mods, but he went so far as to explain in-depth how each part worked so we’d have a solid understanding of how and why each part gained power.

Here’s how we fixed our starving Duramax in three easy mods.

1. Master tech Ethan Barker of Left Coast Diesel helped us install the trio of affordable Duramax fueling modifications that made significant improvements in acceleration on our test truck, especially out of hole.

1. Master tech Ethan Barker of Left Coast Diesel helped us install the trio of affordable Duramax fueling modifications that made significant improvements in acceleration on our test truck, especially out of hole.

2. Here’s the PPE Race Fuel Valve. This affordable upgrade ditches the OEM fuel-pressure relief valve for a solid unit that keeps 100 percent of the fuel in the rail rather than bleeding back off into the tank.

2. Here’s the PPE Race Fuel Valve. This affordable upgrade ditches the OEM fuel-pressure relief valve for a solid unit that keeps 100 percent of the fuel in the rail rather than bleeding back off into the tank.

PPE RACE FUEL VALVE

Common-rail diesels like the Duramax have sky-high fuel pressures north of 20,000psi, and under a heavy load, the factory fuel pressure relief valves are notorious for opening and bleeding off extra fuel-rail pressure back into the system, costing serious power and often times putting the truck into “limp mode.” If that’s not bad enough, once the OEM fuel-pressure relief valves give way, the more often they’ll bleed off pressure until check-engine lights for insufficient fuel pressure become the norm.

But PPE was smart enough to create the fix in the form of the Race Fuel Valve, a simple device made from heat-treated stainless steel that replaces the stock or shimmed pressure relief valve with a solid unit. The PPE unit maintains fuel-rail pressure during prolonged wide-open throttle (WOT) or heavy load situations by directing 100 percent of the fuel to the fuel rail rather than bleeding it back into the system.

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3. Here’s the solid stainless steel PPE upgrade unit on the left compared to the stock unit that is known to bleed off fuel pressure, causing check engine lights and diminished performance under WOT.

3. Here’s the solid stainless steel PPE upgrade unit on the left compared to the stock unit that is known to bleed off fuel pressure, causing check engine lights and diminished performance under WOT.

4. Barker had to dive into the Duramax with both hands and feet to access the fuel pressure relief valve since it’s located on top of the motor just above the bell housing.

4. Barker had to dive into the Duramax with both hands and feet to access the fuel pressure relief valve since it’s located on top of the motor just above the bell housing.

PPE PORTED FUEL RAIL FITTINGS

Would you believe that the Duramax motor is fed fuel through a pair of pinhole-sized feed fittings? That’s right, the GM engineers deemed the kiddy-sized fuel feed fittings necessary for flowing fuel to the rail, and in stock form, they’re right, but the minute enthusiasts start pumping more power into their motors, their Duramax’s start running low on fuel due to insufficient flow.

Again, PPE stepped in with an affordable fix; Ported Fuel Rail Fittings that feature noticeably oversized fuel feed holes so that proper fuel rail pressure during heavy engine loads can be maintained. These stainless steel fittings increase available fuel flow volume from the CP3 to the fuel rail, not only sparing the CP3 from undue wear, but also providing enough fuel for clean, efficient power by relieving rail restrictions on all 2004.5-2010 Duramax LLY/LBZ/LMM motors.

5. With some finagling we got a shot of the elusive unicorn of a bolt. Be careful when removing the bolt, as they have a knack for seizing up and stripping out, which means the quick-and-easy job instantly becomes hours of labor since the fuel rail will then need to be removed.

5. With some finagling we got a shot of the elusive unicorn of a bolt. Be careful when removing the bolt, as they have a knack for seizing up and stripping out, which means the quick-and-easy job instantly becomes hours of labor since the fuel rail will then need to be removed.

6. Here’s a shot of the PPE unit installed and ready to go.

6. Here’s a shot of the PPE unit installed and ready to go.

PPE DIESEL FUEL LIFT PUMP

When Ethan Barker from Left Coast Diesel hooked up a vacuum gauge to our Duramax to read fuel pressure vacuum at idle on our Duramax test truck before and after the PPE Lift Pump, we were simply amazed. In stock form, the truck had 2.5psi of vacuum, but with the pump in place we had 8psi of positive pressure: How’s that for big gains?

Why did we get so much vacuum with the factory setup? Because rather than depending on the OEM CP3 to pull fuel all the way from the stock tank, the PPE Diesel Fuel Lift Pump pushes fuel through the lines and the filter not only to maintain proper fuel pressure in the lines to prevent fuel starvation under heavy throttle loads, but also to eliminate the possibility of air being drawn into the system and reducing stress on the CP3. Insufficient fuel pressure and fuel starvation causes drops in power and excessive smoke, but this ultra-compact powerhouse of a pump from PPE flows up to 160 gallons per hour (GPH) and is compatible with biodiesel, ultra-low sulfur diesel as well as other compatible fuels. The units are made from high-quality billet aluminum with half-inch NPT inlet and outlet lines for maximum flow. They’re also compact, so mounting them between the frame rails or in tight locations is a cinch. The pump motors are nearly silent so gone are the days of loud whining. DW

7. Unlike the OEM fuel rail fittings that feature pinhole-sized fuel feed holes, the PPE ported units are visibly larger to feed a pumped-up Duramax all the fuel it needs. Plus they’re cheap: $34.99.

7. Unlike the OEM fuel rail fittings that feature pinhole-sized fuel feed holes, the PPE ported units are visibly larger to feed a pumped-up Duramax all the fuel it needs. Plus they’re cheap: $34.99.

8. We told you the PPE unit had a visibly larger fuel feed hole: Look at the tiny stock unit on the left compared to the PPE unit on the right.

8. We told you the PPE unit had a visibly larger fuel feed hole: Look at the tiny stock unit on the left compared to the PPE unit on the right.

9. There are two sides to the fuel rail on a Duramax, so two of the ported fuel rail fittings are needed. We begin on the passenger’s side by moving the A/C compressor out of the way to gain access underneath.

9. There are two sides to the fuel rail on a Duramax, so two of the ported fuel rail fittings are needed. We begin on the passenger’s side by moving the A/C compressor out of the way to gain access underneath.

10. Buried underneath some wires and tubes is the passenger’s side fuel line fitting. Simply remove the OEM one and install the PPE unit.

10. Buried underneath some wires and tubes is the passenger’s side fuel line fitting. Simply remove the OEM one and install the PPE unit.

11. Be careful when performing the install, as you don’t want to strip the factory fuel rail; it’s a pain to remove.

11. Be careful when performing the install, as you don’t want to strip the factory fuel rail; it’s a pain to remove.

12. Don’t forget to torque everything to the recommended settings.

12. Don’t forget to torque everything to the recommended settings.

13. The driver’s side fuel rail fitting is located underneath plenty of components so be patient when gaining access to it. Remove and replace the unit just as we displayed for the other side.

13. The driver’s side fuel rail fitting is located underneath plenty of components so be patient when gaining access to it. Remove and replace the unit just as we displayed for the other side.

14. Here’s the PPE Lift Pump. The compact design fits in tight spaces and features a billet aluminum base with a quality, serviceable motor that flows up to 160 gallons per hour (GPH).

14. Here’s the PPE Lift Pump. The compact design fits in tight spaces and features a billet aluminum base with a quality, serviceable motor that flows up to 160 gallons per hour (GPH).

15. The PPE Dual Relay kit allows users to setup their Lift Pump so it only runs when the engine is on, not when the key is, which comes in handy when sitting in the truck listening to the radio with the engine turned off, but the key on.

15. The PPE Dual Relay kit allows users to setup their Lift Pump so it only runs when the engine is on, not when the key is, which comes in handy when sitting in the truck listening to the radio with the engine turned off, but the key on.

16. The PPE high-flow install kit came in handy and made the installation process a bolt-on affair.

16. The PPE high-flow install kit came in handy and made the installation process a bolt-on affair.

17. With the stock components in place, our Duramax test truck idled with a fuel pressure of 2.5psi of vacuum, but that all changed with the addition of the lift pump.

17. With the stock components in place, our Duramax test truck idled with a fuel pressure of 2.5psi of vacuum, but that all changed with the addition of the lift pump.

18. Barker decided to mount the compact pump inside the frame rail where it would be easily accessible and protected from the environment during heavy off roading.

18. Barker decided to mount the compact pump inside the frame rail where it would be easily accessible and protected from the environment during heavy off roading.

19. Measure twice, cut once: Be careful when cutting the fuel lines so as not to remove too much or to collapse the factory hard lines.

19. Measure twice, cut once: Be careful when cutting the fuel lines so as not to remove too much or to collapse the factory hard lines.

20. It’s also a good idea to mount the pump where the motor access panel is easily reached should you someday need to rebuild the motor.

20. It’s also a good idea to mount the pump where the motor access panel is easily reached should you someday need to rebuild the motor.

21. Proper sealant is important when working with NPT lines, but make sure that whatever you use doesn’t get into the fuel stream.

21. Proper sealant is important when working with NPT lines, but make sure that whatever you use doesn’t get into the fuel stream.

22. The Lift Pump comes with all the proper electrical components, and we decided to utilize the Dual Relay kit for added insurance. Don’t forget to solder in the small diodes and other included electrical components.

22. The Lift Pump comes with all the proper electrical components, and we decided to utilize the Dual Relay kit for added insurance. Don’t forget to solder in the small diodes and other included electrical components.

23. Here, Barker tapped into the factory fuse panel for some key-on power.

23. Here, Barker tapped into the factory fuse panel for some key-on power.

24. Note the tidy wiring install with loom, electrical tape and all. The more initial time you spend on the wiring, the better, since having to undo and redo messy wiring is a bear.

24. Note the tidy wiring install with loom, electrical tape and all. The more initial time you spend on the wiring, the better, since having to undo and redo messy wiring is a bear.

25. Here’s the PPE Lift Pump installed and ready for flow. The quiet motor coupled with the rubber mounts makes for a near-silent experience. Seriously, unless you’re listening for it, you’d have no idea it was there.

25. Here’s the PPE Lift Pump installed and ready for flow. The quiet motor coupled with the rubber mounts makes for a near-silent experience. Seriously, unless you’re listening for it, you’d have no idea it was there.

26. With the lift pump and fueling upgrades in place, our fuel pressure at idle went from 2.5psi of vacuum to a positive 8psi. How’s that for a measureable improvement?

26. With the lift pump and fueling upgrades in place, our fuel pressure at idle went from 2.5psi of vacuum to a positive 8psi. How’s that for a measureable improvement?

Sources:

Left Coast Diesel

925-784-9763

Leftcoastdiesel.com

Pacific Performance Engineering (PPE)

714-985-4825

Pacificp.com