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Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 23808
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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I want to know where the signal comes from sent to the ECM

Customer Question

Customer: My name is ***** ***** I want to know where the signal comes from sent to the ECM to fire the fuel injectors on a 90 460.
JA: Thanks. Can you give me any more details about your issue?
Customer: The vehicle is flooding so bad it wont run and wont build fuel pressure. The injectors are going wide open with key on.
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Submitted: 1 year ago.
Category: Ford
Expert:  Tim Mohr replied 1 year ago.

Hi, my name is ***** ***** model is this?

Customer: replied 1 year ago.
It's a 90 E-350 RV
Expert:  Tim Mohr replied 1 year ago.

ok, power to each injector is supplied to each injector with the key on, the PCM then grounds each injector individually to fire each injector, are all the injectors running too rich?

Customer: replied 1 year ago.
Tim, I know the injectors are fired by a driver in the ECM on the ground side.I also know all injectors have 12 volt power with key on. All of the injectors are going wide open with key on which means the driver in the ECM is getting the wrong signal to ground them individually. My question is, where does the ECM get the signal for injector fire ? Is it the stator inside of the distributor ? I don't see where this vehicle has a crank position sensor on it.
Customer: replied 1 year ago.
P. S. The ECM has already been switched out with no positive results.
Expert:  Tim Mohr replied 1 year ago.

Yes, the stator gives the cam signal, but the comuter uses the maf sensor, the oxygen sensor and the coolant temp senor to give the pulse width for the injectors, do you have a fue gauge on it, to see what the actual fuel pressure is?

Customer: replied 1 year ago.
It will not build fuel pressure because as soon as you turn the key on the injectors go wide open. I know this problem is not that complex but my scanner does not give me any data because the vehicle is too old.
Expert:  Tim Mohr replied 1 year ago.

even with the injectors wide open, it should still build pressure, you might have a stuck open regulator, have you disconnected each injector and seen what the pressure does, with all injectors disconnected?

Customer: replied 1 year ago.
The regulator has been changed out. I have not disconnected all the injectors and checked fuel pressure that way. Can you explain to me how it will build fuel pressure with the injectors wide open ?
Expert:  Tim Mohr replied 1 year ago.

even with the injectors all running full rich, it will not cause the fuel pressure to not build, the injectors are not designed like that, can you try discom=nnecting all the injectors and seeing if the fuel pressure build up?

Customer: replied 1 year ago.
Will do
Expert:  Tim Mohr replied 1 year ago.

let me know,Tim

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