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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 757 (ENGINE CONTROLS (TROUBLESHOOTING & DIAGNOSIS) -- 5.7L)TROUBLESHOOTINGFUEL INJECTOR BALANCE TEST WITH TECH 2DESCRIPTION
1999 GMC Forward Control 5.7 R, Automatic

Fuel Injector Balance Test with Tech 2: Description

1999 GMC Forward Control 5.7 R, AutomaticSECTION Description
WARNING: This page is about a different car, the 2004 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.

The scan tool is first used to energize the fuel pump. The scan tool 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 the flow through each injector.

Fuel Injector Balance Test Example (Typical)

Cylinder 1 2 3 4
1st Reading 380 kPa (55 psi) 380 kPa (55 psi) 380 kPa (55 psi) 380 kPa (55 psi)
2nd Reading 215 kPa (31 psi) 201 kPa (29 psi) 208 kPa (30 psi) 229 kPa (33 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
Fuel Injector Balance Test with Tech 2

Step Action Values Yes No
1 Did you perform the Diagnostic System Check-Engine Controls? - Go to Step 2  Go to Diagnostic System Check - Engine Controls
2 Did you perform the Fuel Injector Coil Test? - Go to Step 3  Go to Fuel Injector Coil Test 
3
IMPORTANT: DO NOT perform this test if the ECT is above 94°C (201°F).
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.