Expert: Sean Halliday - 10/13/2009

Question
QUESTION: Hi Sean,
I have a 1994 Ford Mustang,3.8 liter, in my shop.
Came in with a code of number 6 cylinder misfire.
Replaced no. 6 wire and no.6 spark plug(which was fouled).
Code came back.          Removed intake to get at no.6 injector, switched with number 4 cylinder injector.
Started car, code came back, no. 6 misfire.
With the key in the run position, I have a steady stream of fuel from no. 6 injector.
I have power to all my injectors with the key on.
Number 6 is picking up a ground right?
I remove the ground wire for no. 6 , by the ECM and the fuel stopped spraying.
 Here is my question, the fuel driver is in the ECM right?
Or am I looking at this wrong.
The Cam Sensor sends a signal to the ECM ,Ecm says when the injector to squirt.
In 35 years I have yet to replace an ECM on a Ford.
Any help would be appreciated.
Thanks in advance
Tom

ANSWER: Did you do a compression check on #6 cylinder?A fouled plug would not be lack of fuel but more like not burning cleanly.Possibly burnt oil or no compression.This is more like a burnt valve.If you have a good fuel flow from all injectors then this is not the problem.A good spark rules the ignition out as well.

---------- FOLLOW-UP ----------

QUESTION: I did do a compression check on no. 6. All within specs.
Like I said before.........., Number 6 injector is "on" all the time. It is dumping raw fuel, all the time into no. 6 cylinder, with the key on and while the engine is running. The only way I can get this no.6 injector to stop is to disconnect the ground for no. 6

Answer
So the injector was switched to no effect and that would mean the pulse is constant to #6 injector.I have never seen this either on a Ford.You are correct in saying the cam sensor sends the signal to the ecm so,either the ecm or cam sensor could be bad.The cam sensor would not do this as it would not effect only one injector.One other way is to change the ecm with a used from the junk yard.