Have no power to the ground wire of fuel injectors

Tiny
MORRIS1299
  • 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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Thursday, January 12th, 2012 AT 2:03 PM

17 Replies

Tiny
RASMATAZ
  • MEMBER

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

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Thursday, January 12th, 2012 AT 2:42 PM
Tiny
KHLOW2008
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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.

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Thursday, January 12th, 2012 AT 2:57 PM
Tiny
MORRIS1299
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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?

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Thursday, January 12th, 2012 AT 3:05 PM
Tiny
KHLOW2008
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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?

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Thursday, January 12th, 2012 AT 4:40 PM
Tiny
MORRIS1299
  • MEMBER

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.

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Thursday, January 12th, 2012 AT 7:57 PM
Tiny
MORRIS1299
  • MEMBER

Would it be perferable that I should use a volt meter instead when conducting the fuel injector test.

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Thursday, January 12th, 2012 AT 8:02 PM
Tiny
RASMATAZ
  • MEMBER

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

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Thursday, January 12th, 2012 AT 10:08 PM
Tiny
MORRIS1299
  • MEMBER

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.

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Friday, January 13th, 2012 AT 1:55 PM
Tiny
MORRIS1299
  • MEMBER

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.

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Friday, January 13th, 2012 AT 2:01 PM
Tiny
KHLOW2008
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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.

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Friday, January 13th, 2012 AT 3:20 PM
Tiny
MORRIS1299
  • MEMBER

These steps steps you have listed I have tried and the results are as follows:
test light to red wire
ignition on
test light does come on
crank engine
light does stay on

i did disconnect injector wireharness
i attached noid lite
i started cranking engine and light for a less than short blink happened upon cranking and disappeared and never flashed after that.

If this means the pcm is not grounding the circuit what causes this to happen, when prior to this issue the car was parked only due to a power steering hose leak, car was running fine before I parked it. I guess thats besides the point what do I need to do next.

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Friday, January 13th, 2012 AT 4:14 PM
Tiny
MORRIS1299
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I feel that we are so close in getting my car started you guys have no idea how much you are really helping me and I appreciate all the diagnosing steps in walking me through so for now thanks for everthing and I will await you response as to what steps I should take next. PLEASE! And THANK YOU!

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Friday, January 13th, 2012 AT 4:30 PM
Tiny
KHLOW2008
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While replacing the power steering hose, there could be some connectors or ground circuits that had been moved. Recheck those. A bad ground circuit or loose wire connectors can cause the problem.

Check the crank and cam sensors as well. The PCM needs input from these sensors to work the injectors and sparks.

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Friday, January 13th, 2012 AT 5:28 PM
Tiny
MORRIS1299
  • MEMBER

I have tried tracing as much as I could all wires to check if any possible wires are disconnected and I finding a few wire connectors (male) that dont have any (female) atachment connectors that I could see at the moment I am still tryinf to complete my task in tracing wires, but sometimes I feel confused is there a possible way that you could send a wire schematic in identifying wires within the harness from under dash to engine. I'm sorry if its not too much ask, its just that I'm from GUAM and not even the ford dealer out here has a repair manual. Also have another question how do I complete a successful testing on the crank sensor, and the camshaft position sensor using a fluke. What setting do I choose and how do I perform the test, what are the readings supposed to be after completing test. I'm sorry I havent really gotten into the depth of using the volt meter to test senors if they are failing or if its a bad circuit. Please help im really starting to give up, but really need this vehicle to get running, this is my mothers vehicle which stays with her at home in case of emergencies. If you could just breeze through for me the proceedures for testing these parts I will greatly appreciate it, not that I already do cause you have been the best help I have gotten and much appreciation I do have for this so thank you very much in having the time to spendin solving my engine problems. Hopefully I will solve this real soon using your help.

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Saturday, January 14th, 2012 AT 4:43 PM
Tiny
KHLOW2008
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Which engine do you have?
Did you check if there are sparks?
If sparks are not available, it would be a fault with the crak sensor. If the injecttors are not pulsing, it would be cam sensor problem.

It could be coincidence that the engine could not be started after replacement of the power steering hose replacement.

I would try to get the schematic for you but they might be too small to read. Let me have your email so I can send them in pdf format.

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Sunday, January 15th, 2012 AT 7:44 AM
Tiny
MORRIS1299
  • MEMBER

The engine in 4.6L v-8 there is spark but no pulsing at the injectors.

One question I have is that we had a lock smith come out and make keys for the car and he told us that he could not program them would this have any effect on whats going on with the vehicle.

At first we could not find the orginal keys thats why we had him come down and make keys but when he told us he could not program them we went on a hunt for the original keys and found them so we have been using the original keys to try and start the vrhicle.

My email address is : serviceadmin@fleetservicesguam. Com and my name is Jamie L. Morris

once again thanks for all your help.

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Wednesday, January 18th, 2012 AT 11:43 PM
Tiny
KHLOW2008
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The security system can cause non starting.

If there is a fault with the security system, the THEFT indicator light would glow or flash rapidly after ignition key is turned ON.

You would need special tools to program the keys.

I have sent the files to you, hope they are helpful.

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Thursday, January 19th, 2012 AT 4:51 PM

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