Fuel Injectors
Testing
WARNING
Stay clear of all moving engine parts. Do not wear dangling jewelry or loose clothes. Keep
power tool cords or other items that might get caught in a moving part away from fan and
pulleys. Also, do not work on an open fuel system around open flames, welders, or any
device that can cause a spark.
Checking fuel injector operation with the engine running is as simple as listening for a
clicking sound coming from the injectors. Use a mechanic’s stethoscope, or a section of
rubber hose. Place the end of the stethoscope or the rubber hose onto the body of the
injector. Place the stethoscope in your ears, or place the end of the hose against your ear.
An audible clicking noise should be heard; this is the solenoid operating. If the injector
makes this noise, the injector driver circuit and computer are operating as designed.
Continue testing all the injectors this way.
All Injectors Clicking
If you've determined that all injectors are clicking, but the problem is the fuel system
continue diagnostics. Make sure that you have checked fuel pump pressure as outlined.
An easy way to determine a weak or unproductive cylinder is a cylinder drop test. This is
accomplished by cancelling one cylinder at a time, and seeing which cylinder causes the
least difference in the idle. The cylinder(s) that causes the least change is the weak
cylinder(s).
If the injectors were all clicking and the ignition system is functioning properly, remove the
injector of the suspect cylinder and have it bench tested. This is accomplished by checking
for a spray pattern from the injector itself. The injectors are placed in a device that applies
an electrical signal to the injector and a supply of pressurized solvent (not fuel) to check
the spray pattern. If no spray is achieved, replace the injector and check the engine
performance
Summary of Contents for TrailBlazer
Page 1: ......
Page 26: ...Fig 3 Typical body and undervehicle maintenance locations Refer to chart for descriptions ...
Page 29: ......
Page 30: ......
Page 31: ......
Page 175: ...Spring free length check Valve spring squareness check ...
Page 192: ...Front of piston mark ...
Page 361: ...5 3L Engine Except Saab Underhood Fuse Block 2003 2005 Early Production ...
Page 469: ...Removing the outer band from the CV boot Removing the inner band from the CV boot ...
Page 470: ...Removing the CV boot from the joint housing Clean the CV joint housing prior to removing boot ...
Page 471: ...Removing the CV joint housing assembly Removing the CV joint ...
Page 472: ...Inspecting the CV joint housing Removing the CV joint outer snap ring ...
Page 473: ...Checking the CV joint snap ring for wear CV joint snap ring typical ...
Page 474: ...Removing the CV joint assembly Removing the CV joint inner snap ring ...
Page 475: ...Installing the CV joint assembly typical ...
Page 553: ...9 Torque the lug nuts to specification 10 Lower the vehicle ...
Page 556: ...Toe in Frame Misalignment Frame misalignment ...
Page 588: ...Bleeding caliper ...
Page 624: ...Manifold gauge set components Refrigerant recovery recycling station ...
Page 676: ...A C Specifications ...
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