Industrial Injection 631601 Fuel Rail Plug 6.7L Cummins LLY LBZ LMM Duramax

The Industrial Injection 631601 Fuel Rail Plug is a precision-machined performance upgrade designed to replace the factory fuel rail pressure relief valve on common rail diesel engines. The stock pressure relief valve is engineered to bleed off fuel pressure once it reaches approximately 25,000 PSI to protect stock injectors — but over time, or when performance tunes and power adders are introduced, this valve can fatigue or actively work against you by preventing full rail pressure from reaching your injectors.

This solid rail plug eliminates the pressure relief valve entirely, ensuring that all commanded fuel rail pressure is delivered directly to the injectors for improved top-end power and consistent fuel delivery. It is an essential upgrade for diesel owners running tuners, lift pumps, larger injectors, or any modification that demands higher rail pressure than the factory relief valve allows.

Key Features:

• Machined from 304 Stainless Steel for corrosion resistance and long-term durability
• Replaces the factory fuel rail pressure relief valve
• Ensures full rail pressure delivery to injectors — no more pressure bleedoff
• Ideal for use with performance tuners, lift pumps, and upgraded injectors
• Install torque: 70 ft-lbs
• Backed by a 1-Year Warranty from Industrial Injection

Industrial Injection is one of the most respected names in diesel performance, with decades of experience building and validating products on both the street and the strip. Part number 631601 is a direct-fit solution for owners of 2007.5–2018 6.7L Cummins and 2004.5–2010 6.6L Duramax (LLY, LBZ, LMM) diesel applications.