Glacier Diesel Power | 2003-2007 Dodge Ram 5.9L Cummins Big Line Kit

Glacier Diesel Power Big Line Kit | 2003–2007 Dodge Ram 5.9L Cummins CP3 Fuel Supply Upgrade (0306BLK)

Description

Remove one of the most restrictive sections of the factory fuel supply system with the Glacier Diesel Power Big Line Kit for 2003–2007 Dodge Ram 5.9L Cummins trucks.

The factory fuel line connecting the fuel-filter housing to the CP3 high-pressure injection pump uses a hard line measuring less than 1/4-inch inside diameter along with restrictive banjo fittings. While this configuration is adequate for many stock applications, it can become a restriction as fuel demand increases from towing, performance modifications, larger injectors, or higher-output lift pumps.

The Glacier Big Line Kit replaces the restrictive factory plumbing with a full 3/8-inch fuel supply line, stainless-steel adapters, high-quality Push-Lok fittings, Cummins sealing washers, and installation hardware. By increasing the available flow path between the factory filter housing and the CP3, the system reduces restriction and allows the lift pump to supply the injection pump with less pressure loss across the line.

Whether you're maintaining a stock daily driver or building a modified common-rail Cummins, improving the fuel path to the CP3 is one of the simplest ways to remove an unnecessary restriction from the factory fuel system.

Features

• Fits 2003–2007 Dodge Ram 2500 and 3500 5.9L Cummins
• Replaces the restrictive factory hard line
• Upgrades the fuel supply path to full 3/8-inch hose
• Stainless-steel adapters
• Premium 90-degree Push-Lok fittings
• Cummins sealing washers included
• Fuel hose and clamps included
• Direct bolt-on installation
• Designed for factory or aftermarket lift pumps
• Compatible with stock and modified CP3 fuel systems
• SKU: 0306BLK

Why Upgrade the Factory Fuel Line?

The CP3 cannot create high-pressure fuel unless it first receives an adequate supply of low-pressure fuel from the lift pump.

Every restriction located before the CP3 increases the amount of work the lift pump must perform.

The factory system contains several restriction points, including:

• Small-diameter hard line
• Banjo fittings
• Sharp internal passages
• Multiple directional changes

Individually, these restrictions may appear minor. Combined, they create pressure loss between the fuel-filter housing and the CP3.

As fuel demand increases, that pressure loss becomes greater.

The Big Line Kit removes one of the most restrictive portions of the system by replacing the factory plumbing with larger, smoother-flowing components.

Understanding Pressure Loss vs. Fuel Pressure

One of the biggest misconceptions is that a larger fuel line creates pressure.

It does not.

Pressure is produced by the lift pump. The fuel line determines how much of that pressure is lost while moving fuel from one point to another.

A smaller passage creates more resistance as fuel volume increases. A larger passage allows the same volume of fuel to move with less restriction.

The Big Line Kit does not increase lift-pump output. It helps preserve more of the pump’s available pressure by reducing restriction between the filter housing and the CP3 inlet.

Why the CP3 Cares About Supply Restriction

The CP3 is known for being a dependable high-pressure injection pump, but it still depends on a healthy low-pressure fuel supply.

The lift pump must move fuel through:

1. The fuel-tank pickup
2. The supply line
3. The lift pump
4. The fuel filter
5. The factory outlet plumbing
6. The CP3 inlet

Every restriction in this path reduces the pressure and available fuel volume reaching the CP3.

When engine demand rises, fuel flow also increases. As flow increases, the pressure loss created by restrictive fittings and small passages becomes more significant.

This is why some trucks maintain acceptable fuel pressure at idle but experience a noticeable pressure drop under heavy acceleration, towing, or sustained load.

Glacier Tech Tip

The Big Line Kit should be viewed as one part of a complete fuel system, not as a substitute for a weak or undersized lift pump.

If the truck suffers from any of the following, those issues should be corrected first:

• Plugged fuel filter
• Weak lift pump
• Restricted tank pickup
• Collapsing supply hose
• Air intrusion
• Low voltage to an electric lift pump
• Contaminated fuel

A larger line cannot compensate for inadequate fuel supply upstream.

Factory Line vs. Glacier Big Line Kit

Factory Fuel Line

• Less than 1/4-inch internal diameter
• Restrictive banjo-style fittings
• Multiple changes in direction
• Greater pressure loss as fuel demand increases
• Limited flow path between the filter housing and CP3

Glacier Big Line Kit

• Full 3/8-inch fuel hose
• Stainless-steel adapters
• Larger internal passages
• Smoother fuel path
• Reduced restriction
• Improved delivery path to the CP3

The result is a fuel supply path that allows the lift pump to move fuel with less resistance, especially as engine demand increases.

What Problem Does This Kit Solve?

The factory line between the fuel-filter housing and CP3 may become a bottleneck when fuel demand rises.

Common situations where this restriction becomes more noticeable include:

• Heavy towing
• Extended high-load driving
• Performance tuning
• Larger injectors
• Modified CP3 pumps
• Higher-output lift pumps
• Upgraded filtration systems
• Trucks that experience fuel-pressure drop under load

The Big Line Kit removes this small factory section and replaces it with a larger, less restrictive path.

Who Benefits Most?

The Glacier Big Line Kit is useful for stock and modified trucks, but it is especially beneficial for vehicles equipped with:

• Larger injectors
• Modified CP3 pumps
• Dual CP3 systems
• High-output lift pumps
• Performance tuning
• Upgraded fuel filtration
• High-flow tank pickups
• Towing or work-truck configurations

Stock trucks can also benefit from removing an unnecessary restriction, particularly if the factory plumbing is old, damaged, corroded, or leaking.

Can the Big Line Kit Increase Fuel Pressure?

A larger line does not generate pressure. However, reducing restriction can allow more of the lift pump’s existing pressure to reach the CP3.

Some trucks may show a measurable improvement in pressure at the CP3 inlet after the factory line and restrictive fittings are replaced.

Actual results depend on:

• Lift-pump condition
• Lift-pump output
• Fuel-filter restriction
• Tank pickup design
• Fuel demand
• Hose condition
• Existing fuel-system modifications
• Where fuel pressure is measured

The most accurate way to evaluate the improvement is to measure fuel pressure before and after installation under the same operating conditions.

Fuel System Tech Tip

Always compare pressure under load, not just at idle.

A restricted fuel system may show acceptable pressure while the truck is idling in the shop. The problem often appears only when fuel demand rises.

For meaningful testing, monitor pressure during:

• Warm idle
• Normal cruising
• Moderate acceleration
• Heavy acceleration
• Towing
• Sustained uphill operation

A system that maintains pressure at idle but loses it under load may have a restriction, weak lift pump, or inadequate supply capacity.

What Is Included?

The Glacier Diesel Power Big Line Kit includes:

• Stainless-steel adapters
• 90-degree Push-Lok fittings
• 3/8-inch fuel hose
• Cummins sealing washers
• Hose clamps
• Required installation hardware

Applications and Fitment

Fits:

• 2003 Dodge Ram 2500 5.9L Cummins
• 2003 Dodge Ram 3500 5.9L Cummins
• 2004 Dodge Ram 2500 5.9L Cummins
• 2004 Dodge Ram 3500 5.9L Cummins
• 2005 Dodge Ram 2500 5.9L Cummins
• 2005 Dodge Ram 3500 5.9L Cummins
• 2006 Dodge Ram 2500 5.9L Cummins
• 2006 Dodge Ram 3500 5.9L Cummins
• 2007 Dodge Ram 2500 5.9L Cummins
• 2007 Dodge Ram 3500 5.9L Cummins

Designed for trucks equipped with the 5.9L common-rail Cummins diesel engine.

Important Compatibility Notes

• Not compatible with trucks equipped with a Jacobs exhaust brake.
• A separate Jacobs-exhaust-brake-specific Big Line Kit is required for those applications.
• Designed for 5.9L common-rail Cummins engines only.
• Verify the existing fuel-system configuration before ordering.
• Compatible with most factory and aftermarket lift-pump systems that retain the factory fuel-filter housing.
• Confirm that the truck has not already been modified with alternate CP3 inlet plumbing.

Installation Notes

Before installation:

• Clean the area around the fuel-filter housing and CP3.
• Prevent dirt from entering open fuel fittings.
• Inspect the fuel filter and replace it if the service history is unknown.
• Remove and discard the original sealing washers.
• Verify that all supplied adapters match the intended ports.
• Route the hose away from exhaust heat, sharp edges, and moving components.
• Make sure the Push-Lok fittings are fully seated.
• Avoid twisting or kinking the hose.
• Prime the fuel system before extended cranking.
• Inspect every connection for leaks after startup.
• Verify fuel pressure after installation.

Do not overtighten adapters or fittings. Excessive torque can damage threads, sealing surfaces, the fuel-filter housing, or the CP3 inlet.

Important Notes

• This kit replaces the fuel line between the factory fuel-filter housing and CP3.
• It does not replace the complete fuel supply system.
• It does not increase lift-pump capacity.
• It does not correct a plugged filter or restricted tank pickup.
• It is not compatible with Jacobs-exhaust-brake-equipped trucks.
• Verify fuel-system routing before ordering.
• Use the supplied sealing washers.
• Check for leaks after installation.
• Monitor fuel pressure when diagnosing supply problems.
• SKU: 0306BLK

Common Failure Point: Restrictive Banjo Fittings

Banjo fittings are compact and convenient for factory assembly, but their internal passages can be considerably smaller than the hose or hard line connected to them.

Fuel entering a banjo fitting must change direction and pass through cross-drilled internal passages before exiting the fitting.

At low fuel demand, this restriction may not be obvious. As flow increases, the pressure loss across the fitting becomes more significant.

Replacing the small factory line and restrictive fittings helps create a more direct fuel path between the filter housing and CP3.

Common Failure Point: Diagnosing the CP3 Before Checking Supply

A truck that experiences low rail pressure, reduced power, or pressure-related trouble codes does not automatically have a failed CP3.

The high-pressure system depends on the low-pressure system.

Before replacing a CP3, inspect:

• Lift-pump operation
• Fuel-filter condition
• Tank pickup
• Supply hoses
• Air intrusion
• Electrical voltage to the lift pump
• Fuel pressure at the CP3 inlet
• Factory line and banjo restrictions

A supply-side restriction can reduce the amount of fuel available to the CP3 and create symptoms that appear to be a high-pressure pump problem.

Is This the Correct Kit for Your Truck?

This kit is likely the correct choice when:

• The truck is a 2003–2007 Dodge Ram with a 5.9L Cummins.
• It retains the factory fuel-filter housing.
• You want to replace the restrictive filter-to-CP3 line.
• The truck is not equipped with a Jacobs exhaust brake.
• You are upgrading the lift pump or filtration system.
• You are experiencing pressure loss between the filter housing and CP3.
• You want a larger 3/8-inch fuel supply path.

This may not be the correct kit when:

• The truck has a 6.7L Cummins.
• The truck is equipped with a Jacobs exhaust brake.
• The factory filter housing has been removed.
• The truck already uses custom CP3 inlet plumbing.
• The fuel system has been completely rerouted.
• The actual problem is a failed lift pump or restricted fuel filter.

Complete Your Fuel System

Pair the Glacier Big Line Kit with the appropriate fuel-system components:

• Glacier Fuel Boss mechanical lift-pump system
• Glacier MK-2 Micro-Kleen filtration system
• Fuel-pressure sender tee
• Fuel-pressure gauge
• High-flow fuel-tank pickup
• Replacement fuel filter
• CP3 inlet adapters
• Fuel-system test fittings
• Replacement supply hose
• Fuel-pressure warning switch

The Glacier Diesel Power 0306BLK Big Line Kit removes the restrictive factory line between the fuel-filter housing and CP3 and replaces it with a full 3/8-inch fuel path. By reducing pressure loss and improving the available flow path, the kit helps the lift pump deliver fuel to the CP3 with less restriction.