Fuel Injector Balance Test
FUEL INJECTOR BALANCE TESTA fuel injector tester is used to energize the injector for a precise amount of time, thus spraying a measured amount of fuel into the intake manifold. This causes a drop in the fuel rail pressure that can be recorded and used to compare each of the fuel injectors. All of the fuel injectors should have the same pressure drop within a variance of 10 kPa (1.5 psi).
Injector Balance Test Example
Test
1. An engine cool down period of 10 minutes is necessary in order to avoid irregular readings due to hot soak fuel boiling.
2. Connect the fuel pressure gauge carefully to avoid any fuel spillage.
3. The fuel pump should run about 2 seconds after the ignition is turned to ON.
4. Insert a clear tube attached to the vent valve of the fuel pressure gauge into a suitable container.
5. Bleed the air from the fuel pressure gauge and hose until all of the air is bled from the fuel pressure gauge.
6. The ignition switch must be OFF at least 10 seconds in order to complete the powertrain control module (PCM)/engine control module (ECM) shutdown cycle.
7. Turn the ignition ON in order to get the fuel pressure to its maximum level.
8. Allow the fuel pressure to stabilize and then record this initial pressure reading. Wail until there is no movement of the needle on the fuel pressure gauge.
9. Follow the manufacturer's instructions for the use of the adapter harness. Energize the fuel injector tester once and note the fuel pressure drop at its lowest point. Record this second reading. Subtract it from the first reading to determine the amount of the fuel pressure drop.
10. Disconnect the fuel injector tester from the fuel injector.
11. After turning the ignition ON, in order to obtain maximum pressure once again, make a connection at the next fuel injector. Energize the fuel injector tester and record the fuel pressure reading. Repeat this procedure for all the injectors.
12. Retest any of the fuel injectors for which the pressure drop exceeds the 10 kPa (1.5 psi) variance specification.
13. Replace any of the fuel injectors that fail the retest.
14. If the pressure drop of all of the fuel injectors is within 10 kPa (1.5 psi), then the fuel injectors are flowing normally and no replacement is necessary.
15. Reconnect the fuel injector harness and review the symptom diagnostic tables.
CAUTION:
- The fuel system is under pressure. To avoid fuel spillage and the risk of personal injury or fire it is necessary to relieve the fuel system pressure before disconnecting the fuel lines.
- Do not pinch or restrict nylon fuel lines to avoid damage that could cause a fuel leak, resulting in possible fire or personal injury.
NOTE: In order to prevent flooding of the engine, do not perform the Injector Balance Test more than once (including any retest on faulty fuel injectors) without running the engine.