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Home >> Pontiac >> 2005 >> Aztek Base, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - 3.4L - Troubleshooting & Diagnosis >> Troubleshooting >> Fuel Injector Balance Test with Special Tool >> System Description

System Description

The scan tool is first used to energize the fuel pump relay. The fuel injector tester is then used to pulse each injector for a precise amount of time allowing a measured amount of fuel into the manifold. This causes a drop in system fuel pressure that can be recorded and used to compare each injector.

Fuel Injector Balance Test Example (Typical)

Cylinder 1 2 3 4
1st Reading 296 kPa (43 psi) 296 kPa (43 psi) 296 kPa (43 psi) 296 kPa (43 psi)
2nd Reading 131 kPa (19 psi) 117 kPa (17 psi) 124 kPa (18 psi) 145 kPa (21 psi)
Amount of Drop 165 kPa (24 psi) 179 kPa (26 psi) 172 kPa (25 psi) 151 kPa (22 psi)
Average Range: 156-176 kPa (22.5-25.5 psi) Injector OK Replace fuel injector- too much fuel pressure drop Injector OK Replace fuel injector- too little fuel pressure drop