This is a complete fuel pump assembly designed for the V12 BMW E31 models, including the 850i, 850ci, and 850CSI, specifically for M70 engines (1990-1994) and S70 engines (1992-1997). The assembly is located beneath the passenger rear seat and includes a top rubber seal. To clarify, this product is not a 3D printed part. It has undergone over two years of development, with every component being precision injection molded to match factory standards, effectively addressing the shortcomings of the original design. The following changes and improvements have been made to the original design: 1. A significant issue with the original fuel pump assemblies (for both 850 and 840 units) is that up to 50% begin to leak fuel at the mold "parting line" located at the top of the assembly, just below the injection point mark. Over time, thermal expansion and contraction can cause micro cracks to develop along this line, resulting in fuel leakage. The new design eliminates this problem by providing a top cap that is universally strong and crack-resistant. 2. The original BMW pump assembly features brittle plastic preformed fuel lines that connect to rubber hoses and subsequently to the fuel pump motor. While this design may have been acceptable 30 years ago, the introduction of modern, more corrosive fuels, such as E10 in Europe and ethanol additives in the US, has led to rapid degradation. This degradation results in significant pressure leaks at the fuel pump motor connection and through cracks in the old plastic lines, causing rough idling, low power on one or both banks, and lean running conditions. The new design significantly improves upon the original by utilizing high-pressure fuel-resistant corrugated PTFE lines that run directly from the top of the pump unit to the pump motors, eliminating the need for rubber hoses. These lines are heat-pressed onto the fuel pump fittings and clamped to ensure there are no pressure leaks. 3. The original BMW wiring is insulated with a material that only partially resists regular fuel, particularly E10. Over time, the wires can delaminate, creating electrical shorts. This assembly uses 600v military-grade PTFE insulated wire, which is designed to last significantly longer within the tank. Additionally, the ground wire connection has been redesigned to eliminate the exposed crimped 1 to 2 wire split joint, reducing the risk of shorting. 4. The original BMW fuel pump motors are equipped with copper commutators, which have been replaced with modern, quiet carbon commutator motors that last three times longer in fuel while maintaining the factory 3 BAR pressure precisely. 5. The fuel level sensor, although similar in shape to the original, has been re-engineered with modern components to enhance precision and longevity the 4 original NBR pump shocks have been upgraded with viton rubber that will last much longer even in modern corrosive fuel.. A standard one-year full parts replacement warranty is included with this assembly.
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