I only have one working injector. The drivers side injector only sprays on start up. Everyone tells me it could be something other than the injector but no one has been clear on what it could be.

I am trying to find out what EXACTLEY I should look for or test for? Or should I just buy a new injector and be done with it?

Seems to me if it is spraying momentarly on start up then it can't be the electrical connector or the fuse.

Is there a fuse somewhere other than in the fuse box I should be looking for?

Thanks in advance.

 

You'll have to do a bit of troubleshooting with DVM or a test light. Basic injector circuit is very simple:


One side of injector is tied to ignition +12 volt source and the other is pulled by ECM to ground to close (fire) injector. TBI injectors have low impedance coil with DC resistance measured around 1.0 to 1.2 Ohm (with 2mH inductor in series). This requires circuit inside ECM to be able to pull down momentarily up to 4 Amps, but once injector is actuated (open and delivering fuel) holding current can be reduced down to 1.5Amps or less. Enough of theory.

1) Check injector coil resistance with a DVM. This might be tricky since contact resistance between test leads and injector terminals might be high. But try getting a good contact - look for 1.1 to 1.5 Ohms on your DVM. If one significantly different from the other you found your dud.

2) Check voltage presence with engine running on both "A" terminals. Terminal B is the ECM side and a test light should be flickering. With engine stopped, ignition on both terminals (A & B) should be around 12 volts.

3) Once you figure which injector is not firing verify that 12 volt is present at the respective ECM header pin ( Either D16 or D14) If there is no 12 volts at ECM and Pin B is at 12 Volt check circuit 467 or 468 for damage.

4) If there is 12 volt present at D16 or D14 then injector driver circuit inside ECM has been damaged (switching transistor has been zapped or there is an open trace some where on PCB)

//Alex

 

Thanks Alex

 

if not , try witchunterperformance they do a great job @ cleaning injectors .

 

i had the same problem with my firebird. i just ran the red to the white so they both had 12 volts and they fire eveytime. might not be the proper way but it will work till i get a ecm