The fuel injectors not working why?

Did you test for spark? I would check spark and fuel pressure. OK, here's a little bit of working theory that'll help you to see the ‘why’ of the Noid light test.

Whether you're testing a No Start Condition or a Misfire Condition, you'll need to know if the cause of the problem is a lack of fuel. When your GM 3.8L (Buick, Chevrolet, Oldsmobile, Pontiac) does not start, it will be either because of a lack of fuel or spark. The same thing goes for when your GM 3.8L equipped car or mini-van is misfiring... that specific engine cylinder isn't contributing to engine power because it either lacks fuel or spark.

Now, since the above two conditions (No Start and Misfire) can be caused by any number of things... one of the things that has to be eliminated, from this list of possibles, is the fuel injector not getting power or the injector pulse signal (On/Off switching signal) from the vehicle's Computer.

This is where the fuel injector Noid light test comes in handy, because you're able to visually see if both of these signals are present or not. If no flashes, then now you know that you have to verify that the connector is getting power (12 Volts) and the injector pulse signal.

One thing to keep in mind, is that the fuel injector Noid light test does not test for a BAD fuel injector. But, is the first step in verifying if the fuel injector is BAD or not. For the fuel injector test tutorial.

no signal for the injectors
check cam/crank position sensors
check immobilizer operation
check ecm and harness connections

the ecm controls the pulse of the injectors. use a noid light to see if the pulse signal is present in the injector circuit

Hi there:
You will have to pinpoint what the engine is missing... Spark / Fuel / Compression


All three of these are tested when the engine is being cranked over. There are two way of checking for fuel. Fuel pressure and fuel trigger. Both are very important and must be present for the engine to start. Fuel pressure is self explanatory. You just hook up the gage and see what the reading is. Fuel trigger is check with a noid light. The injector gets unplugged and the noid light gets plugged in to the injector clip. With the engine cranking over, this light must blink. This is the signal to the injectors from the computer. You can have all the fuel pressure in the world, but it wont matter if the injector is not pulsing gas into the cylinder like it should.


Compression tester, spark tester, fuel pressure gage and noid light are all accessible at your local auto store. All three tests play a very important part in diagnosing a no start condition. Be extremely careful when doing these tests.


Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.


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check fuel pump pressure,then injector signal, you will need a pressure guage and noid light

CHECK FUEL PUMP AND FUEL INJECTOR FUSE.IF FUSE IS GOOD.YOU NEED A NOID LIGHT TO CHECK TO SEE IF INJECTORS FIRING.YOU CAN BUY A NOID LIGHT AT ANY AUTO PARTS PLACES.WHAT YOU DO DISCONNECT FUEL INJECTOR CONNECTOR.HOOK NOID LIGHT TO CONNECTOR.CRANK ENGINE TO SEE IF NOID LIGHT BLINKS.IF YES INJECTORS FIRING.IF YOU GET STEADY LIGHT.PCM NOT WORKING NOT FIRING INJECTORS.IF YOU GET NO POWER OR LIGHT DONT WORK.YOU HAVE A WIRING PROBLEM.YOU NEED A HAYNES REPAIR MANUAL LOOK AT THE ELECTRICAL WIRE DIAGRAM.TO TRACE FAULTY WIRE.

you need to remove the connector on one of your fuel injectors and install a noid light turn engine over and see if noid light flashes do not use test light it has to much resistance and can damage injector drivers inside pcm you can have spark and fuel but if pcm does not command injector to open no start

check for spark at coil if you have spark check for injector pulse at injector with noid light..if noid light does not flash check for power at one side of injector connector ..if you have 12 volts at injector connector but no flashing of noid light replace ignition control module under distributor cap

Maybe a problem with the theft deterrant system. My Tahoe had a similar intermittant problem and the dealer said there was a fault in the theft system and it would shut off the fuel pump.

you need a noid light and check injector signal to start