Mechanics

HAVE NO POWER TO THE GROUND WIRE OF FUEL INJECTORS

1999 Ford Mustang • 72,580 miles

Car sat for about a month because it had a power steering hose leak, I bought a new power steering hose and replaced it, and after replacement car wouldnt start, ran several test to the fuel system and found no problems with power to the fuel pump, I had bypassed the relays and directed power to the pump, the pump wasnt working, so I replaced the pump and now works properly. Vehicle still will not start, did several testings and found that with ignition on and not cranking the power line to fuel injectors is good, but when testing the ground side of wire and did a crancking test I had noticed no flashing of test lght, so I'm guessing that, this is the problem, but my question is I have performed many testing to several electrical wire circuits and do know that the fuel injectors work but still not getting any signal of flashing power to ground side of injector harness plug to injector. I dont know what more to do can someone please help me?
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Morris1299
January 12, 2012.




Possible the injector ground driver/s of the computer or wiring problem

Tiny
Rasmataz
Jan 12, 2012.
If you use a normal test light to test the injector pulsing, you are not going to get anything.

You need a noid light to detect the pulses.

KHLow2008
Jan 12, 2012.
So how do I test the ground driver of the computer, do I just follow the steps of disconnecting all the injector plugs and single test one by one until I loose signal to pin point the faulty injector, if so what does this have to do with the driver and how do I test the driver itself. Also whats the difference in a noid light and normal test light, and is it easy to find a noid light?

Tiny
Morris1299
Jan 12, 2012.
You can get the noid light from parts stores. Normal test lamp requies a high voltage to light and the pulsing of the injector circut is too fast for the test light to be able to show.

When engine is running, the computer wuld ground the injector circuit to operatethe injectors. Do you have battery voltage to the injector wire harness?

KHLow2008
Jan 12, 2012.
When you say battery voltage to the harness are you refering to voltage when the ignition switch is on not crancking if so than I do have battery voltage to the harness.

Tiny
Morris1299
Jan 12, 2012.
Would it be perferable that I should use a volt meter instead when conducting the fuel injector test.

Tiny
Morris1299
Jan 12, 2012.
Use the noid lite on the injector harness if it doesn't flash its either no powwer to it or the computer is not driving it or wiring problem

Tiny
Rasmataz
Jan 12, 2012.
I ran another test today I located a noid lite and conducted a test and this was my outcome. I first started with one injector it has constant power with ignition switch on (no cranking) I reversed polarity to test pulse power and initially found no pulse when cranking, I disconnected all injector wire harness and still got no pulse power during the cranking process. When ignition is in the on position and your just about to full turn key to crank engine it has a quick may quarter of a second power to pulse side, than as you continue to crank engine all power is like cut off. I had also connected a OBDII diagnostic reader and it pulled a code (fuel rail pressure sensor high output)i think if I rember correctly code was (P0194). After attempting these procedures I plugged back injectors and tried cranking engine again and it wanted to start(it almost started) but just couldnt get it to run. Please help me as to where will turn to next in checking or to diagnose, im getting lost here it seems at times.

Tiny
Morris1299
Jan 13, 2012.
Sorry I got that trouble code wrong and data it said (P0193 Fuel Rail Pressure Sensor Circuit High Input) is this sensor located directly on top of the fuel rail (driver side) and what does this normally mean that this sensor needs replacing. Also there were no other codes listed only this one.

Tiny
Morris1299
Jan 13, 2012.
P0193 can be due to disconnected fuel pressure sensor hose. It can also be caused by excessive cranking without engine starting so we should not worry about this as it is the injectors that are not working.

Lets try this.

With test light connected to injector RED wire.
Turn ignition on.
Test light should come on.
Crank engine.
Test light shoudl remain on. If not, you have a ower supply interruption and it could be a faulty ignition switch.

Disconnect injector wireharness.
Attach noid light across the two terminals.
While cranking engine, the noid light should flash, if not, the PCM is not grounding the circuit.
AD

KHLow2008
Jan 13, 2012.

AD