How do I test the Fuel Injectors on an LT1

[drexel_j]

I have an LT1 with Painless wiring harness and a 1992 computer. It just stopped running the other day; the spark is good but I don't feel like the injectors are opening properly (I do have 43 PSI at startup). How do I test the Injectors from the computer, I think I might have a bad computer (I just put in a rebuilt computer about a month ago).

[mario_82_ZXT]

To see if they are firing you can buy (or make) a little noid lamp that goes into the connector.

 

If the light pulses then the injectors are firing.

 

You can also ohm out injectors. The manual should have an acceptable range of values.

Mario

[80LS1T]

Your injectors should ohm out at around 12-15ohms. As for testing them, you should really use a "noid" light" but you can use a 12V test light. The noid light is designed not to put any extra load/draw on the injector circuit so you dont run the risk of damaging the computer. So using a 12V test light may or may not damage your PCM. I've seen plenty of guys use it without any harm to the PCM.

 

The first thing I would do is check your fuses on your harness. I know the factory harness has two 7.5A fuses, one for each bank of injectors.

 

 

Guy

[mark]

how old is the opti spark?

[drexel_j]

The Optispark is new; I tried connecting an extra injector and I could never feel the solenoid click, I tried the 12 volt light, it was very sporadic and dim.

[azguy]

I would double check my grounds for the pcm, battery, engine to frame. Bad grounds do funny stuff. Other than that it could be a bad icm. As far as I know there is not a way to test a icm. It was a toss of either opti or icm for me 2 times. Both times it was the opti.