I have a 89 formula with a 90 vette tpi motor in it. I had a short in the circut that runs all the lights and somehow, since fixing this short. Several of the fuel injectors are refusing to fire. Has anyone had this problem, or know a way to fix it. Could this be ecm/prom related, or just bad wires somewhere?
Ive traced the wires and they all appear to be good, my mechanic swears that he thinks its in the computer, i replaced it, same problem, replaced the chip, same problem. Is there something that im missing? Any help would be appreciated, right now all i have a paper weight.

 

All the injectors in that era tie into just one injector driver in the ecm. So it's all or nothing, with an ocassional nothing.

What can happen is low resistance injector overheats the driver, and makes it operation intermittent. The easy first thing to do, is ohm out the injectors. They should be no less then 12 ohms.

 

did it sit up for very long?
if they check good on resistance & you have a good signal to them & it has sat up, they may be stuck closed.
its not uncommon for the injectors to stick after sitting for an extended period of time. i had 4 or 5 of mine stick after sitting for about 6 months or so. with the motor running, lightly tapping on them with a wrench freed them right up.

 

Mechanic says the injectors are getting the constant 12v what its not doing is grounding. Two of the injectors are refusing to ground, and therefore not working. Im wondering could the actual connectors on the wiring harness be bad? any ideas?
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It also has only been out of action for 5 weeks total, inculding down time for the burnt wires whiel the car still ran ok.

 

The ECM supplies the ground to fire the injectors. The power is always there (just liek most of the other sensors in the car, the dome lights, etc.)

So, you still need to check the resistance (not voltage) and make sure all the injectors are in the 12-16 ohm range.

Wait a min...

How did the mechanic determine only 2 injectors were not getting a ground signal? Did they use a noid light? Are the 2 they identified adjacent to each other (like 2 and 4, or 5 and 7)?