Typically, the leak test of fuel rails is performed with the use of a Tracer Leak detector in the 500 -03 sensitivity range.  However, there are some applications that are less or more sensitive. Most Tier Suppliers will require a production rate of110 parts per hour and are typically tested in a Small Hard Vac or Small Hard Vac customized system. 

Key Considerations for the accurate and repeatable test of fuel rails are:

• High or low pressure
• Need to accommodate both sub-assembly (L/R) and full assembly
• With and without injection influences sealing/fixturing design

Vacuum Instruments Corporation has been designing and manufacturing customized systems to test these parts as well as other Power Delivery Applications for decades. During this time, we have developed and innovated several System, Test and or Fixturing differentiators, including:

• Interchangeable chambers/carts allowing asset repurpose/multiple programs
• Smaller footprint than competitors
• Aluminum Billet design allows the chamber to repurpose for high or low pressure

AUTOMOTIVE FUEL TANK SOLUTIONS OFFERING

• Integral tooling for product sealing
• Stainless steel charge lines
• Easy change over with removable fixtures
• Enhanced evacuation and vent schemes to improve cycle time
• Calibrated gas leaks installed on chamber/s for process checks
• Auto-calibration provides direct reading of part leakage

Specification example for Automotive Fuel Tank Assembly

• Leak Rate – 5 x 10^-5 atm-cc/sec He
• Tracer Gas Test Pressure – 1 to 2 psia with a maximum pressure differential of 2 psia
• Tracer Gas Concentration – Dynamic calculation based upon actual pre-charge pressures
• Leak Detector – MD-490M
• Test Method – Hard Vacuum
• Machine Cycle – 70 seconds

Leak testing of fuel tanks can be complex.

Careful attention to the test-part pressure is critical.  Damage to the parts’ integrity and part distortion can easily occur without precise pressure monitoring.  At VIC we specialize in proven techniques to ensure proper part evacuation and charging during the entire leak test process.

Our well established hard-vac leak testing capabilities provide reliable and repeatable leak test results on critical fuel tank applications.  Our live helium part percentage correction techniques allow for accurate leak rate readings, even with the challenge of low pressure charging as found in fuel tank applications.  Part support and fixturing are also critical items that VIC has demonstrated experience in for accurate leak testing of fuel tanks.

AUTOMOTIVE FUEL RAIL SOLUTIONS OFFERING

• Maximum allowable leak rates usually range in the 10-4 Atm-cc/sec range
• High production rates
• Multi-step process with vacuum decay gross test followed by tracer gas fine test
• Customized ergonomic tooling fixtures with automatic sealing
• High pressure gas handling system
• Accurate and repeatable measurements for reliable results of leak testing

Lower fuel consumption requirements warrant the need for high pressure fuel injection.  Fuel rails need to be tested for leaks during component production at a supplier level to prevent leakage in the engine compartment. 

High-pressure, direct-injection fuel rails have a maximum allowable leak rate spec of 10^-4 atmospheric cubic centimeters per second (atm-cc/sec).  Leak testing fuel rails with helium, often with the fuel injectors installed, in a vacuum chamber is a common process.

A fuel rail is essentially a tube that delivers gasoline to individual fuel injectors in an internal combustion engine.  Formerly, vehicle manufacturers designed fuel rails to withstand pressures of only 30 to 60 psig, a minimum requirement for port injection.  Nowadays, to meet more stringent standards for fuel economy, emissions, and efficiency, fuel rails have been redesigned to withstand much higher pressures—up to 5,000 psig and beyond.