I got a code that said #4 injector open cycle, misfire. I removed fuel rail and turned key to on, #4 injector would not stop spraying. I switched injectors and redid test. The the same results. Since it's not the injector, what else could it be?

 

Signal from the computer

 

If you have individually fired injectors, it's most likely the PCM (computer). The driver has failed.

If you have a batch setup, it's wiring -- because the other injectors fire OK. It COULD be wiring with an individually fired setup, but probably not.

If it is the PCM, you should probably still get the injector checked out. It may have overloaded the drive circuit and caused the failure in the first place.

Good Luck,

hj

 

I pulled out fuel rail turned key on and that one injector would not stop spraying. I switching the injector and that same thing happened. I have constant voltage at that injector plug, I think its only a few volts. I have an anolag meter it was set to 2.5 volts. The key was not on. I don't think its the wiring because there's no place it touches the engine. PCM then?

 

There's always voltage,
PCM grounds to complete the circuit and open the injector.

Chafed wire or bad computer.

 

Thanks, so if I pull all my injector plugs off without the key on will they all have 12 volts ?

 

Without the key?

No, no I don't think so.
Sorry if I misstated.

But there should be constant power in run or start.

 

I did a ohms test I got a complete curcuit. With constant power to the plug does that cancel out the chafed - wire. I have a chance to use a Snap On scanner tomarrow, is there anything that will tell me if the PCM is bad?

 

If you have power to the injector and a short to ground on the other wire the injector will always stay open.
Test ohms to ground on the 'cold' side.

A lot of good info here; Fuel Injection Technical Library

 

Thanks, I did the ohms test from + to - on the injector connector. Are you saying ohms test the connector, + to the engine block. Then injector connector - to the block ?

 

- on the harness to the block or some other ground.
If you have continuity look through the harness.
If it's not touching somewhere, then test the PCM or just replace it.

 

thanks so much.

 

ArdWrknTrk That injector was continuously on for about a mile, will I need to change the oil? I had fuel comming out of the exhaust to. If I unplug the injector can I drive it about 6 miles, to get it home?

 

One mile? how much time is that?
injectors are rated in pounds per hour.
I would be more concerned about cylinder washdown.

Is the oil thin? Does it smell like fuel?
People with failed mechanical fuel pumps have driven with crankcases overflowing with gasoline.
I think it will be okay.

 

Means that the power source to the injector is not there. The PCM grounds the injectors, so it is looking for a feedback signal, and when it is not there it will set a fault code. You will need to determine where the injector is getting it's power supply and correct that issue.

I found this on the net is this a correct statement? I have constant power at connecter, with out key.