With the car running, I disconnected power to each injector. When injectors 2 and 3 were disconnected, the car began to die, and no change occurred when 1 and 4 were disconnected. I then put a test light on the plugs for injectors 1 and 4, which have two terminals. Plug 1 had no power to either terminal. Plug 2 had constant power (the light did not blink) at both terminals, but when one of the terminals was tested, the engine started to die. Would this be a problem with the harness or with the controller?
For reference, the car is a 1991 Pontiac Grand Am with a 2.3L DOHC (Duel OverHead Cam) Quad-4 engine that has an Integrated Direct Ignition system.One fuel injector getting no power, another getting constant power?The ecu or computer under the dash is what controls the FI . Flooding the motor could have shorted some thing in the computer .Go to the parts store and get another one and plug it in!One fuel injector getting no power, another getting constant power?Quad Four engines are VERY troublesome. This is why they are no longer on the market!! There could be corrosion in your wiring harness. You could even have a bad head gasket (very common on these) that is causing a ground problem for your injectors. Pull your plugs, and look for signs of discoloration indicating that your head gasket is sucking coolant. GM should just give you a newer car. When I was a dealership technician, these poor cars kept coming in over and over again with NO real solutions made. Good luck!!One fuel injector getting no power, another getting constant power?You have the answer already in your question....it's either the harness or the computer.
As a future precaution - do not use a test light on computer controlled components - the test light has a very low impedance and can easily present what is essentially a short circuit to the computer. There are high impedance LED test lights and volt meters available to test these circuits.Injectors 1 and 4 are on one circuit, 2 and 3 on another; they are all powered up through the same wire by the computer, and each circuit is grounded in alternating fashion to feed the fuel to the engine in the best manner. So you should have constant power from the computer to one wire of each connector, but you will read power at both wires since it will back feed through the wiring to the other wire. The hot wire should be gray, the grounding wires blue or green depending on which circuit. That being said, it seems you have power from the computer to both circuits but it is somehow being disrupted, maybe a wire is burned through and shorted. Tough to find these things sometimes. I would start by following the wiring loom from the injectors back and looking for something wrong. Good luck.
