The Fass II fuel system is a high-performance upgrade for diesel engines, specifically designed for 1998.5–2002 (VP-44) and 2003 and newer (CP-3) 5.9L Cummins engines. This system enhances fuel delivery, improves engine performance, and reduces the risk of fuel starvation. Installing the Fass II fuel system involves precise routing of fuel lines, correct mounting of the pump, and proper connection of the wiring harness. This guide draws from the detailed instructions provided in the source documentation to ensure a reliable and correct installation.
Overview of the Fass II Fuel System
The Fass II fuel system is a comprehensive upgrade that includes a high-capacity fuel pump, a pre-filter, and all necessary fittings, connectors, and wiring. It is designed to replace the original equipment manufacturer (OEM) lift pump in Cummins engines and is compatible with both the 98.5–02 (VP-44) and 03 and up (CP-3) model years.
Key components of the Fass II kit include:
- A high-flow electric fuel pump
- A fuel pre-filter for debris removal
- High-quality fuel lines and connectors
- A wiring harness with a relay and inline fuse
- Mounting hardware and zip ties for securing components
The installation process requires attention to detail, particularly in aligning the pump’s orientation and ensuring that all connections are secure and leak-free.
Pre-Installation Preparation
Before beginning the installation, it is important to gather all the necessary tools and materials. These typically include:
- A set of Allen wrenches
- Zip ties (15–20)
- Thread lock compound
- A small amount of motor oil for lubricating O-rings
- A wrench or pliers for tightening bolts
- A multimeter or test light for electrical checks
The kit comes with most of the required components, but users should ensure they have the additional zip ties needed for securing the fuel lines and wiring harness. It is also recommended to have a clean workspace and sufficient lighting to ensure accuracy during the installation.
Mounting the Fass II Pump
The first step in the installation is to mount the Fass II pump to its bracket. The pump has two orientation indicators: a "T" for the tank-side fitting and an "E" for the engine-side fitting. It is crucial to align these correctly, as improper installation can lead to premature wear and void the manufacturer’s warranty.
Orientation and Positioning
- Markings on the Pump: Locate the "T" and "E" markings on the pump. The "T" port should point toward the fuel tank, and the "E" port should point toward the engine.
- Mounting Bracket: Use the four bolts provided in the kit to secure the pump to the mounting bracket. Ensure that the small hole next to the electric motor on the base of the pump is aimed directly toward the ground. This positioning is critical for the pump’s longevity and proper function.
Securing the Pump
Once the pump is aligned and positioned, use the four bolts from the kit to fasten it to the bracket. Apply thread lock compound to the threads before tightening to prevent loosening over time. The manufacturer emphasizes the importance of this step, as improper installation can lead to mechanical failure.
Fuel Line Installation
After mounting the pump, the next step is to install and route the fuel lines. The Fass II kit includes pre-cut fuel lines and connectors for ease of installation. The process involves connecting the suction line from the fuel tank to the pump and the discharge line from the pump to the fuel filter housing.
Suction Line Setup
- Taping the End: Before beginning, tape off the running end of the new fuel line to prevent dirt and debris from entering the system.
- Connecting to the Tank: Attach the new connector to the other end of the line and click it onto the pickup tube nozzle where the OEM line was removed. This ensures a secure connection and prevents fuel leakage.
- Routing the Line: Stretch the line toward the inlet side of the Fass pump. Cut the line to the appropriate length and install the fuel pre-filter between the tank and the pump. The pre-filter should be placed in a convenient location to allow for future maintenance.
Discharge Line Setup
- Connecting to the Pump: Connect the supplied fuel line to the discharge side of the Fass pump.
- Routing Toward the Engine: Route the line toward the engine compartment. For 98.5–02 models, the line should be mounted up to the fuel filter housing inlet using the new connector provided. For 03 and up models, the filter block adapter must be installed on the back side of the fuel filter housing using two original Allen bolts.
Ensuring a Leak-Free Connection
Before tightening the filter block adapter, check that the OEM O-ring is in place and apply a small amount of oil to prevent it from rolling during installation. This helps to create a watertight seal and prevents fuel from leaking around the connection. Use two of the original mounting bolts and apply thread lock compound to secure the adapter in place.
Electrical Wiring and Harness Installation
The Fass II fuel system includes a wiring harness that connects the pump to the vehicle’s electrical system and the engine control module (ECM). Proper routing and connection of the harness are essential to ensure the pump operates correctly and safely.
Connecting the Harness to the Pump
- Identifying the Harness: Locate the end of the wiring harness that connects to the Fass pump. Route the harness down through the engine compartment toward the pump.
- Securing the Connection: Slide the connector onto the pump and use zip ties to secure both the wiring harness and the fuel line from the pump to the fuel filter housing. This prevents the harness from becoming dislodged during operation.
Connecting to the ECM
- Routing the Other End: Find the other end of the harness, which clips into the original wiring connection from the ECM to the OEM lift pump.
- Securing the Connection: Route the harness properly and clip it into place. Use zip ties to secure the connection and prevent movement or strain on the wires.
Relay and Power Connections
- Mounting the Relay: The relay provided with the harness can be mounted in a location away from heat sources. A common mounting spot is the firewall, along with the inline fuse.
- Connecting Power and Ground: Route the power and ground feed wires around the firewall and connect them to the positive and negative battery terminals. Trim any excess wiring to ensure a neat and secure installation.
After completing the electrical connections, it is important to inspect all wiring and connections for any signs of damage or improper routing. A loose or damaged wire can lead to electrical failure or even a fire hazard.
Final Checks and System Purging
Before starting the engine, it is important to perform a final inspection of the entire system to ensure all components are correctly installed and secured. This includes checking the fuel lines, wiring harness, and pump mounting.
Leak Check
Start the truck and check for any signs of fuel leaks. This is a critical step, as even a small leak can lead to significant issues over time. If a leak is detected, turn off the engine immediately and inspect the affected area.
System Purging
Since the fuel system may contain air, it is important to purge it before starting the engine. This can be done by bump-starting the truck without allowing the engine to run. Once fuel begins to flow out of the drain tube, close the drain valve and turn the key off. Repeat the bump-start process to ensure all air is purged from the system.
After purging, the Fass II pump should be able to circulate fuel effectively and maintain consistent pressure to the engine. This helps to prevent fuel starvation and ensures optimal engine performance.
Maintenance and Troubleshooting
The Fass II fuel system is designed for long-term reliability, but regular maintenance is still necessary to ensure its continued performance. Key maintenance tasks include:
- Filter Replacement: The fuel pre-filter should be replaced at regular intervals to prevent clogging and ensure clean fuel flow.
- Wiring Inspection: Periodically check the wiring harness for signs of wear, corrosion, or damage.
- Pump Inspection: Inspect the pump and its mounting for any signs of vibration or loosening.
If any issues arise, such as low fuel pressure or unusual engine behavior, the following troubleshooting steps can be taken:
- Check for Leaks: Inspect all fuel lines and connections for signs of leakage.
- Inspect the Pump: Ensure the pump is securely mounted and functioning properly.
- Test the Electrical System: Use a multimeter or test light to verify that the pump is receiving power and that all electrical connections are intact.
Conclusion
The Fass II fuel system is a reliable and effective upgrade for 5.9L Cummins engines. By following the detailed installation instructions provided in the source documentation, users can ensure a smooth and successful installation. Key steps include proper pump orientation, secure mounting, careful fuel line routing, and precise electrical connections. Regular maintenance and troubleshooting can further enhance the system’s performance and longevity. With the Fass II fuel system in place, users can enjoy improved fuel delivery, enhanced engine performance, and reduced risk of fuel-related issues.