Engine Picture Differences Lbz Lly
Identifying Problems Early and Bulletproofing 2004-2006 Chevy HD/GMC Diesel HD Trucks
The LLY Duramax engine found on 2004-2006 Chevrolet/GMC HD trucks is the second generation of the Duramax line. It can last hundreds of thousands of miles, but it still has its fair share of issues. Thankfully, the LB7 injector problems were resolved, but some new problems revealed themselves. Some of these 6.6L LLY Duramax engine problems stem from the fact that it has significantly more horsepower and torque compared to the original Dmax. Much of this superior performance is attributed to its massive variable vane turbocharger, the biggest turbo ever found on a Duramax truck.
The LLY Duramax also came at a time when emissions regulations began to become stricter. For that reason, they had to include a problematic EGR system to comply with emissions regulations. Like every other diesel out there, the emissions additions result in problems and lesser reliability. These two components aren't the root of all LLY Duramax Problems though. In fact, a number of other common 6.6L LLY Duramax problems exist.
Thanks to the aftermarket, most of these problems can be solved relatively easily. You just need to have a little mechanical know-how. Solving many of these problems will not only improve longevity and durability, but they can often improve performance too. So, if you're looking to improve your LLY Duramax in more ways than one, you've come to the right place. Here is a list of the 11 most common LLY Duramax problems and how to fix them.
What Are the Most Common 2004.5-2006 6.6L LLY Duramax Problems And How Do You Fix Them
Most Common LLY Duramax Problems
If you want to jump to a specific section, simply click on any of the bullet point links below.
- Turbo Inlet Manifold
- Head Gasket Failure
- Injector Harness Chafing
- Water Pump Failure
- Overheating
- EGR Valve Problems
- Glow Plug Failure
- Fuel Pressure Relief Valve
- Suspension/Steering Problems
- Bent Rods
- Lack of a Factory Lift Pump
1. Turbo Inlet Manifold
The LLY Duramax utilizes a Garrett variable vane turbocharger (VVT) that has a bigger turbo compressor wheel and taller vanes than other Duramax generations. This makes it a prime candidate for aftermarket upgrades like a tuner. Unfortunately while this turbocharger provides significant air-flow, the LLY Duramax has several components that are extremely restrictive, resulting in problems because of it. The main restriction is the turbo air inlet manifold.
The LLY Duramax turbo air inlet manifold, sometimes called the turbo mouthpiece, forces the turbocharger to work harder than it needs to. It does this by essentially choking the turbo because of its small, restrictive design, forcing it to work harder to produce the same amount of boost. This results in excess heat and EGTs. It also provides less than optimal performance and fuel economy.
How To Fix the LLY Duramax Turbo Inlet Manifold Problem
Thankfully, fixing the turbo inlet manifold is as simple as replacing it with a less restrictive aftermarket part. This will not only help your truck run cooler, but it will also free up some extra horsepower and torque! Turbo spool-up times are reduced too. All in all, it translates into better drivability, reliability and performance. Any of the Turbo Inlet Manifold kits listed below will do the trick!
AFE Turbo Inlet Manifold '04-'05 LLY
Improve air flow by 73% over stock with the AFE Turbo Inlet Manifold for 2004-2005 LLY Duramax trucks. AFE claims this product offers gains of 23 horsepower and 57 lb-ft of torque.
2. Head Gasket Failure
Head Gasket Failure is more common the LLY Duramax than any other Dmax generation. This is largely due to the huge factory turbocharger and overheating issues caused by a poor cooling system. There are other factors that can play a role too though. Aftermarket modifications can also cause these issues, especially at lower mileage. Here's how the different factors I just listed can play a role in blown head gaskets on your LLY.
The Turbocharger
Because of it's size and flow characteristics, the Garrett VVT Turbocharger makes experiencing head gasket failure significantly more common. The higher boost and performance can eventually lead to head gasket failure because it increases wear and tear. This is especially true if your truck still has the factory turbo mouthpiece or turbo inlet manifold. Its restrictions cause excess heat and force the turbocharger to work harder than necessary.
Overheating
The LLY experiences more overheating compared to other generations of the Duramax diesel because of its inadequate cooling system. They have the smallest radiators and fans found on any Duramax diesel truck. Pair this with a high-flowing turbocharger with a number of restrictions and its kind of like the perfect storm.
This is especially the case under heavy loads or when it's extremely hot outside. Fluid temperatures spike under these conditions which brings increased wear and tear on the factory head gaskets.
Other Causes of Head Gasket Failure
Tuning and other performance mods can also cause head gasket failure. Horsepower and torque isn't free! Improving performance comes at the price of higher EGTs and drive pressures. These can result in premature head gasket failure, so be very careful when adding any aftermarket upgrades.
Common Signs of Blown Head Gaskets
- Unexplained Loss of Coolant
- Visible leaks in the engine bay or on the floor
- White Smoke
- Engine overheating
- Oil contamination
Fixing Blown LLY Duramax Head Gaskets
If you experience head gasket failure on your LLY Duramax, it's probably best to take your truck to a shop. Unfortunately, it's going to be an expensive ticket. Most shops will charge you 30-40 hours of labor because replacing the factory head gaskets is extremely tedious. Numerous components have to be removed including your injectors, glow plugs, EGR, exhaust components and more.
Other than the obvious new head gaskets you will need, you should also consider upgrading the head bolts to ARP head studs. These offer significantly more clamping pressure and they can pretty much guarantee you won't have the same problem more than once. Since you will be removing the injectors and glow plugs, this is also a good time to address those if you're having issues.
ARP Head Stud Kit
For most applications, ARP Head Stud Kit 230-4201 is all you need. This head stud offers significantly more clamping force than stock. If you want to avoid head gasket issues on your LLY again, consider these a must-have.
ARP Head Stud Custom 625+ Kit
If you are looking to maximize horsepower and torque, build a sled-pulling or race truck, you should use ARP's Custom 625+ Head Stud Kit instead. This is made for performance applications and it'll give you the greatest longevity.
3. Injector Harness Chafing
As LLY Duramax trucks on the road are only getting older, more and more are being found to have injector harness chafing. Vibrations, heat, and just general wear and tear cause the injector harness to rub against other vehicle components until the wiring gets exposed.
Here's what you need to look out for if you suspect you are having issues with your LLY's injector harness.
Common Signs of Injector Harness Chafing
- Rough Running
- No Start/Rough Start
- Power Reduction
- Diagnostic Trouble Codes (DTCs)
The factory harness tends to go bad on the #7 and #2 injectors. Depending on how bad the problem is, you may be able to fix the wiring rather than having to replace the entire injector harness. If you can't identify the problem however, or if it can't be salvaged, you're going to have to replace the entire thing.
How to Fix Injector Harness Chafing
If you injector harness is bad, you will likely have to replace it. You can find a new replacement harness directly below. It's upgraded so it prevents the problem from occurring again.
4. Water Pump Failure
Water pump failure is a relatively common weak point on Duramax trucks. While the seal issues found on LB7 trucks have been largely solved, the LLY Duramax can still suffer from water pump failure. Over time and at higher mileage, the seals in the factory water pumps can fail. This frequently occurs after 80-100,000 miles. Early model LLY Duramax engines experience less water pump problems than late models however. This is because in 2006, the impellers were switched over to plastic from cast iron. This makes them significantly less reliable.
How do you know if your water pump might have failed? These are common symptoms when you have a bad waster pump.
Signs of Water Pump Failure
- Overheating
- Coolant Loss
- Visible Coolant Leaks
Fix Your LLY Duramax Water Pump Problems
The water pump is one of the most dreaded problems found on these trucks because of how much of a pain they are to fix. So even if you get 100,000 miles out of your original one, you should still be dreading when your water pump eventually does fail. When this inevitably happens, you can either replace it with another factory water pump, or a quality aftermarket one. Replacing it with another factory water pump should give you another 80-100,000 trouble free miles. Aftermarket ones can last substantially longer however, as they correct the design flaws of the original water pumps.
Here are a couple of our favorite replacement water pumps for the LLY Duramax.
'01-'05 GM OEM Duramax Water Pump
Sometimes, factory parts can be more reliable than aftermarket ones. While there are some aftermarket alternatives that improve on the factory design of the LLY Duramax water pump design, the OEM water pump, GM 97228188 is still better than most cheap alternatives on the market.
'06-'16 Duramax Water Pump Kit
If you have a 2006 model LLY Duramax, this is the OEM Water Pump you will need to use. They changed designs in 2006 and the new part number is GM 12637105.
Merchant Automotive Water Pump Kit
If you're looking for one of the highest quality Water Pump replacement kits for your LLY, this is it. The MA Water Pump Kit has both the drive gear and impeller tig-welded to the shaft for extra durability and to prevent wretched impeller walk. It also comes with seals, gaskets, and flywheel lock for a complete job!
5. LLY Duramax Overheating
The most notorious problem found on LLY Duramax trucks is that they have a tendency to overheat. Part of this is attributed to their inadequate cooling system, that's made up of the smallest radiator and fan ever found on a Duramax diesel truck. Severe air restrictions that choke the large, variable vane turbocharger also cause excess heat, causing the trucks to run a little warmer. When paired with extreme conditions like a really heavy trailer or very hot temperatures, the factory LLY cooling system may not perform well enough. If left unchecked these high temperatures can result in more serious problems.
Despite these issues, a majority of LLY Duramax overheating is actually caused by other common LLY Duramax problems. Blown head gaskets, water pump failure, fan clutch failure, and even a dirty or clogged radiator can be the root cause of your overheating issues. So if you're experiencing overheating problems, it's best to rule these issues out before investing significant money into updating your cooling system.
Fixing LLY Duramax Overheating Problems
If you find one of the issues above is the reason for your overheating problem, you should address the problem as soon as possible! Here is a list of replacement parts to help you.
| Part Name | Part # |
| Right Head Gasket | GM 12637788 |
| Left Head Gasket | GM 12637785 |
| Fan Clutch 2004-2005 2006 | Varies GM 15130067 GM 15102145 |
| OEM Radiator 2004.5-2005 2006 | Varies GM 89018318/21490 GM 15914079/21686 |
| OEM Water Pump 2004.5-2005 2006 | Varies GM 19168888 GM 12637105 |
If you've determined that your truck's factory cooling system is the cause of your overheating problems, there are quite a few aftermarket upgrades that can significantly help prevent overheating. Here are some of our favorite upgrades that should help you keep coolant temperatures down and also net you better performance.
Performance Radiators
In response to the inadequate cooling system found on the LLY Duramax, numerous manufacturers sought to improve on the very flawed factory design. Problems mostly exist with early 2004 and 2005 trucks, as in 2006 the Duramax was overhauled and outfitted with a superior cooling system. This makes it even more important if you have an early LLY to upgrade your cooling system. That doesn't mean you won't have to upgrade a 2006 Duramax radiator though. Over time, your radiator can collect all kinds of build up, or even develop leaks or damage. Here are some of our favorite LLY Duramax radiators available on the aftermarket.
2004-2005 Dmax AFE BladeRunner Radiator
AFE's Bladerunner Performance Radiator for 2004-2005 LLY Duramax trucks offer 25% greater core size for improved cooling and are made of aircraft grade aluminum with tig-welded aluminum end tanks.
2006 Dmax AFE Bladerunner Radiator
Even though the '06 Dmax has a better cooling system, that doesn't mean it can't be improved upon. The 2006 LLY Duramax AFE Bladerunner Radiator 25% thicker core for better cooling efficiency and its made of aircraft-grade aluminum.
2001-2005 LLY Mishimoto Radiator
The 2004-2005 Mishimoto LLY Duramax Performance Radiator offers increased cooling efficiency, greater durability, and a lifetime warranty. If your factory radiator is falling apart or just not meeting cooling demands, check this thing out!
2006 Mishimoto LLY Performance Radiator
For 2006 LLY Dmax trucks, Mishimoto makes an upgraded performance radiator offering even better performance. Just because the factory cooling system was improved, doesn't mean it's perfect! If you need a new radiator, consider upgrading with this one from Mishimoto.
Intercoolers
Upgraded intercoolers provide your LLY Duramax engine with cooler, denser air. This results in cleaner combustion, lower EGTs, and gains in performance. During the EGR process, coolant is used to help lower these exhaust gas temperatures even further. At higher EGTS, coolant can experience breakdown. Lowering EGTS helps reduce coolant breakdown and it also has a ton of other benefits too like increased fuel economy.
Many intercooler upgrade kits like the Bank's Power Technicooler also come with upgraded boost tubes. Together, these products reduce restrictions caused by poor OEM designs and greatly improve air flow. If the intercooler you're looking to purchase doesn't come with them, consider purchasing them too! Check out some of our favorite Intercooler Upgrade Kits for the LLY below.
Bank's Techni-cooler Intercooler '04-'05
Bank's Power Techni-cooler Intercooler Upgrade Kit for the '04-'05 LLY Duramax diesel provides significantly cooler air than the factory intercooler and also removes factory restrictions. In fact, this intercooler offers 25% greater volume and 34% greater volume than the stock system! The result is more power, greater fuel efficiency, and improved reliability.
Bank's Techni-Cooler Intercooler Kit '06
Bank's Power offers a 2006 LLY/LBZ Duramax Techni-Cooler Intercooler Kit as well! If you want cooler, denser air for your late model LLY Duramax, this is the kit for you. Pair this kit with Bank's Boost Tube upgrade kit for even more performance gains!
Bank's Power Boost Tube Upgrade Kit
For 2004.5+ LLY/LBZ Duramax trucks the Bank's Boost Tube Upgrade Kit offers vastly improved performance over the stock boost tube. It's the perfect partner to their techni-cooler intercooler, but it can also be used with the factory intercooler!
6. EGR Problems
Like most early emissions devices, the EGR system proved to be a common LLY Duramax problem. The EGR system, or exhaust gas recirculation system lowers emissions by re-introducing exhaust gasses back into the engine. This helps reduce NOx levels before it's emitted from the tailpipe.
The EGR system is made up of two components, the EGR valve and the EGR Cooler. The EGR Valve regulates the amount of exhaust being recirculated and also controls when recirculation occurs. The Cooler is responsible for cooling these exhaust gases before they are re-routed into the engine. EGR coolers use coolant to reduce the temperatures of these exhaust gases.
While this system does successfully reduce NOx emissions, coolant degradation can occur from the extreme heat of the exhaust temperatures. Carbon and soot build up can also occur in the EGR cooler or EGR valve. This can result in outright failure. These issues are nowhere near as common as they are in the 6.0L Powerstroke. They still do occur however, especially in higher mileage engines.
Fixing EGR Problems
If your EGR system is acting up, it could be time for an overhaul. EGR Delete kits are an easy, inexpensive solution but they are not legal modifications on street driven, registered vehicles. They are allowed on race trucks though! So if your vehicle isn't street driven, this is a valid option.
If you're like me and you rely on your truck for commuting and for work though, you're going to have to replace your EGR system with aftermarket alternatives or replace the kit with OEM products. Because the EGR system on the LLY Duramax isn't nearly as problematic as that of the 6.0L Powerstroke, I wouldn't hesitate to use OEM parts. The parts tend to last quite a long time! There are some really good aftermarket alternatives however, that have proven themselves. Here are some of the different EGR upgrades you should consider for your LLY.
Sticking With A Stock EGR System
There's nothing wrong with the factory EGR System if you like keeping OEM parts! The LLY Duramax doesn't suffer the same widespread EGR problems like the 6.0L Powerstroke.
LLY Duramax OEM Emissions Components
| Part | Part # And Link To Buy |
| EGR Valve 2004.5-05 2006 | Varies by Year GM 97303761 or ACDelco 2142109 GM 98025695 |
| EGR Valve Gasket 2004.5-05 2006 | Varies By Year GM 97303655 GM 98054443 or GM 97303655 |
| EGR Cooler 2004.5-05 2006 | Varies by Year GM 97303654 GM 97358507 |
7. Glow Plug Failure
LLY Duramax Glow Plug failure is a common problem amongst late model year trucks. The factory glow plug controllers have been found to overcycle the glow plugs which could result in glow plug damage. The tips of the glow plugs can actually break off inside the engine, resulting in a worst case scenario of catastrophic engine damage. There is no way of suspecting damage until this issue actually occurs though. Fortunately for us, the likelihood of this happening now is very slim.
GM fixed the issue by reprogramming factory glow plug controllers to prevent this issue from happening. For that reason, it's likely your LLY Duramax already has this problem resolved. If you have bought a truck that has extremely low in mileage, it may be worth bringing the truck in to the dealership just to verify that the reprogramming has occurred.
8. LLY Duramax Fuel Pressure Relief Valve (FPRV) Problems
The Fuel Pressure Relieve Valve, or FPRV, is a small, but annoying LLY Duramax problem. The FPRV is a plug that utilizes a small spring to relieve fuel rail pressure when it gets too high. This is a great safety measure GM implemented, but over time, especially if your vehicle has power levels greater than stock, the FPRV can become a problem.
After repeated use, the spring becomes weaker and weaker, until it gets to a point where it can no longer sustain even stock pressures. This part wears even faster on modified trucks or even just LLY Duramax trucks with a tuner. Here are some common symptoms of a weak FPRV.
Signs That Your FPRV isn't Working Properly
- Loss of power during full throttle driving
- P0087 DTC (Code)
- P1093 DTC (Code)
Thankfully, this is a relatively cheap fix. You'll learn the solution to the Duramax FPRV problem in the next section.
How to Fix your LLY Duramax Fuel Pressure Relief Valve (FPRV) Problem
There are three relatively inexpensive ways to solve a poorly working Duramax fuel pressure relief valve. The three FPRV fixes are installing a FPRV shim kit, replacing your FPRV with a race fuel valve, or replacing your FPRV with another OEM FPRV.
1. Shim Kits
The cheapest way is by installing a shim kit that adds shims to the factory FPRV. Most shim kits only cost $10-$30 and this is the preferred fix for daily driven trucks. It will restore the factory FPRV to hold up to pressure at or above its original levels. It will also still retain the FPRV as a safety measure to prevent damage from occurring on your truck.
PPE FPRV Shim Kit
PPE's FPRV Shim Kit offers everything you need to fix your factory fuel pressure relief valve problems.
BD FPRV Shim Kit
Another good shim kit we recommend to fix problems associated with your factory FPRV is the BD FPRV Shim Kit.
2. Race Fuel Valves
The second mentioned method is by scrapping the FPRV altogether and installing an LLY Duramax Race Fuel Valve. This is also an easy fix and involves removing the factory FPRV and replacing it with a plug that will not derate or release pressure at all. While this will solve the problem permanently, it doesn't retain the factory safeguard of an FPRV and should only be used in race applications. Here are some of our favorite LLY Duramax Race Fuel Valves.
PPE Race Fuel Valve /w O-Ring
Remove that old FPRV with the PPE Race Fuel Valve! We like this kit because it comes with an O-ring and it's inexpensive.
BD Common Rail Fuel Plug
Although it has a different name, the BD Common Rail Fuel Plug is designed to do the same thing! This is another kit that comes with an O-Ring too!
3. New OEM Fuel Pressure Relief Valve
The last fix to a worn out factory FPRV is by simply racing your worn out one with a new OEM replacement. This is another easy fix, but if your truck is heavily modified you will be doomed to the same problem eventually! This is a good fix for stock trucks, it's just significantly more expensive than either of the two options listed above.
9. IFS Suspension/Steering Problems
Like other Duramax generations, the LLY Duramax has an independent front suspension and is susceptible to common problems associated with this front end type. The IFS system used gives your LLY Duramax a phenomenal ride, but it doesn't help much in terms of durability.
Independent front suspensions have their fair share of issues and weak points. They become especially prevalent once you put bigger tires, wheels, or modify the factory suspension. Even a leveling kit can cause these issues.
So what exactly are these issues? Tie rod failure, steering geometry problems, premature wear and tear on all components, and loose steering due to worn pitman/idler arms are the most common issues. Luckily enough, there are aftermarket solutions for just about all these problems!
Broken Tie Rods
Broken tie-rods are a common Duramax problem. The factory tie rods are built extremely thin and not suitable of a heavy duty truck. Off-roading or even just normal wear and tear can cause the factory tie rods to fail.
The best way to address the factory tie rods is by replacing them with aftermarket ones. If you compare the two side-by-side you will find the factory unit has a fraction of the thickness of any aftermarket replacements. Cognito and Kryptonite are two companies that offer quality aftermarket tie rod kits.
Cognito Alloy Series Tie Rod Kit
The Cognito Alloy Series Tie Rod Kit improves tie rod durability and also offers more articulation than factory units. Photo taken from Cognito Motorsports Website.
Kryptonite Tie Rod Kit
Kryptonite's '01-'10 Duramax Tie Rod Kit offers a beefier, more durable design that is hard to beat. Through Kryptonite's testing they found their Tie Rods to hold up to 2.5X the pressure of the factory tie rods.
Upper Control Arms: Correcting Steering Geometry problems
When you add a leveling kit to your LLY Duramax, you're very likely throwing your steering geometry out of whack. By cranking your torsion bars you're adjusting the factory angles that are designed for optimal performance and ride quality.
Adding a leveling kit may give you some extra clearance, but it could also severely reduce ride quality and cause premature wear and tear on your front end components. This could result in ball joints and other components failing way faster than normal.How do you fix steering geometry issues and bring back ride quality? Replacing the upper control arms on your LLY can bring back everything into factory specs and improve ride quality.
If you are thinking about leveling your LLY, or if it is already leveled, you should definitely invest in a set of upper control arms. Cognito and Kryptonite both make quality upper control arms that are a huge improvement over stock. Many people also choose to upgrade their shocks at the same time for superior dampening control. Fox and Bilstein shocks both make quality shocks that pair very well with these kits.
Cognito Box-Style UCA Kit
Cognito's Box-Style UCA Kit for '01-'10 Duramax trucks corrects ball joint angles, improves droop travel, and also slightly increases caster for better highway drivability.
Kryptonite UCA Kit
The Kryptonite '01-'10 Duramax UCA Kit offers a lifetime, no questions asked warranty. These UCAs also fix common problems attributed to leveling a duramax truck.
Pitman/Idler Arm Problems
Early pitman and idler arm failure is one of the LLY Duramax truck's common steering problems. This is due to forward and rearward movement of the center link. Over time, your steering can become loose from too much play. You'll also notice excessive wandering, or even play in the steering wheel.
A PISK kit, or pitman and idler arm support kit, can solve these problems and make your steeling feel brand new. They do this by replacing some faulty factory components and also by adding support to the pitman and idler arms. This reduces the play found between these components and the factory center link. For a couple hundred dollars a PISK kit is a must-have.
Cognito PISK Kit
The Cognito PISK Kit reduces play between the pitman arm, idler arm, and center link. This reduces the life expectancy of these parts and improves steering feel.
Kryptonite Pisk Kit
Kryptonite's PISK Kit offers the same benefits at a similar price, greatly improving steering feel and reliability.
If it's too late for your factory pitman or idler arms, aftermarket companies like Kryptonite and Moog make solid aftermarket replacements that will hold up better. Here's some quality aftermarket replacement Pitman and Idler Arms. You can also visit our LLY Duramax Maintenance page for more steering and suspension related parts recommendations and OEM part numbers.
Kryptonite Death Grip Pitman Arm
Kryptonite's Death Grip Pitman Arm uses more heavy duty internals and features a stronger design than factory unit. Make sure you check whether you need a 3-spline or 4-spline pitman arm. Most Dmax trucks utilize a 3-spline, but some may need a 4-spline unit which you can find here.
Kryptonite Death Grip Idler Arm
Kryptonite's Death Grip Idler Arm provides greater durability and tighter steering feel than factory units. It also comes with a lifetime warranty.
10. Bent Rods
Bent rods aren't a common LLY Duramax problem unless you modify your truck's performance. After about 500 horsepower, the factory rods can bend. While their forged steel design prevents them from snapping which would result in significant engine damage, this is still an issue that will be expensive to repair. Because of the LLY's favorable performance characteristics when compared to the LB7, we see more LLY Duramax trucks with issues. The huge factory turbocharger makes it easy to achieve these horsepower milestones with just tuning and a few inexpensive supporting modifications.
Fixing And Preventing Bent Rods on an LLY Duramax Engine
There are basically two solutions to bent rods on these trucks. The easiest, and least expensive way, is to not modify your truck heavily beyond performance levels. If you have tuning, keep it at a lower setting and don't dog your truck. If this isn't an option, be prepared to fork over some serious cash. The other option is replacing the OEM rods with aftermarket ones.
11. Lack Of Factory Lift Pump
Like most other Duramax trucks, the LLY Duramax is not equipped with a factory fuel lift pump. Fuel lift pumps are the low pressure pumps that are responsible from drawing fuel from the tank and supplying the injection pump with constant fuel pressure. Because there is no fuel lift pump on the LLY Duramax, the CP3 injection pump is responsible for getting fuel from the tank, as well as pressurizing it and supplying it to the injectors. This results in significantly more wear and tear on the CP3 injection pump. Thankfully the CP3 is pretty capable and reliable, so failure isn't a common problem on lower mileage trucks.
The lack of a fuel lift pump really begins to show when you begin to upgrade your LLY Duramax. With advanced tuning and other performance mods, you'll need a constant supply of fuel or else you won't really reap the rewards of your performance upgrades. A loss of fuel rail pressure can occur during acceleration. What good are your mods then? Fuel Lift Pumps solve this problem by providing a constant flow of fuel and they can even be adjusted or purchased to support higher fueling needs.
Solving the Problem: Just Add A Lift Pump
The only way to fix this problem is by adding a fuel lift pump! They're not super expensive and they can make a huge difference, even on a stock truck. Whether your truck is stock or modified, fuel lift pump systems come as a lift pump/fuel filtration system kit. They provide much better fuel filtration than your standard fuel filter. This translates into your engine burning cleaner fuel. The result is lower emissions, improved fuel economy, and most importantly extended fuel system life. Who isn't happy about adding to the lifetime of your expensive fuel system components? Here are some of our favorite aftermarket Lift pumps for the LLY Duramax.
Air Dog II-4G 100 GPH Lift Pump
For lightly modified truck or stock ones, the Air Dog II-4G 100 GPH Lift pump is a perfect match. It helps eliminate air in your fuel lines, provides better fuel filtration, and takes the pressure off of your factory CP3 injection pump by supplying a constant fuel supply.
Air Dog II-4G 165 GPH Lift Pump
For higher performance LLY Duramax diesel engines you need a higher flowing pump. The Air Dog II-4G 165 GPH Lift Pump meets the higher fuel demand and provides the same benefits as other models.
Learn More About the LLY
Want to learn more about the second generation Duramax engine? Visit some of our other resources by clicking on one of the links below or in the sidebar.
Engine Picture Differences Lbz Lly
Source: https://dieselresource.com/diesel-resources/lly-duramax-problems/