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I am having the same fuel injector curse it looks like many…

I am having the same...
I am having the same fuel injector curse it looks like many others have had. Truck is a 1990 F250 with a 7.5L/460. I have spark and compression and have set timing. I have check all grounds that I can find. I have battery voltage at the eec relay, in and out. Ground looked poor so I gave it a temporary good ground. I have even replaced the ecu in desperation. I have power on both wires at the injector with the ignition on. If I supply a ground to either wire the injector opens and I can hear and see fuel enter the cylinder. Here's the interesting part. After supplying the injector with a ground I loose my battery voltage on the other wire until I cycle the key. Ideas?
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Answered in 5 days by:
11/16/2017
Chris (aka- Moose)
Chris (aka- Moose), Technician
Category: Ford
Satisfied Customers: 53,338
Experience: 16 years experience
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I am sorry no one has helped You slipped through the cracks or all have viewed and passed. Is there more you can add to your post which may help us more so we can help you. Another option is to just write out another concern you may have and we can try to help on that. I do not want you to feel like we are a scam or avoiding you. We want to help you but we want to make sure the help we provide is not in vain and you will be pleased.

Chris

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Customer reply replied 9 months ago
I am not sure what addition information I can give. I thought I was fairly thorough. Maybe the whole message didn't come through? If that was the case I will cut/paste the original. If you already have the info please let me know what additional information you would like. Thanks for responding.
I am having the same fuel injector curse it looks like many others have had. Truck is a 1990 F250 with a 7.5L/460. I have spark and compression and have set timing. I have check all grounds that I can find. I have battery voltage at the eec relay, in and out. Ground looked poor so I gave it atemporary good ground. I have even replaced the ecu in desperation. I have power on both wires at the injector with the ignition on. If I supply a ground to either wire the injector opens and I can hear and see fuel enter the cylinder. Here's the interesting part. After supplying the injector with a ground I loose my battery voltage on the other wire until I cycle the key. Ideas?

When you lose voltage on the red wire to the injector with the key on. Is the red wire at the idle air bypass solenoid also no longer powered?

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Customer reply replied 9 months ago
I will check when I get home this evening. Thanks

Fine by me.

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Customer reply replied 9 months ago
Sorry for the delay is getting back to you. We have had some nasty cold weather here. I went back out and supplied ground to the injector. This time I did not lose power like before. Maybe the first time I check it my back probe wasn't as tight as I thought and I only thought I lost power. I checked the red wire at the idle air bypass valve and it also has power.

So is the fuel injector now working?

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Customer reply replied 9 months ago
No, the injectors are still not working. I made my own led test light and back probed the injector. It flashes on/off when cranking but no fuel is getting into the combustion chamber. The light is somewhat dim when it flashes on. The only thing I can think of is the ground signal from the pcm is weak?

An injector test with a test light is not as efficient as one done with a noid light. If you are getting battery voltage to the injectors and a ground pulse. You can check for a poor ground to the PCM, though I believe the injector may be bad or clogged.

Now that I have posted a partial or complete answer, you will see you can rate me. The deposit you have already paid is not transferred to me until you rate me. I would like to receive nothing less than 5 star excellent ratings. So if we are not there yet, please reply and let me help more. If you're not pleased, let me know because rating bad does not result in a refund, there are better options. Rating now will not close this post nor prevent replying. Thanks Chris

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Customer reply replied 9 months ago
I have no problem rating you at 5 stars. However, I would like to get a little farther on the diagnosis.
I didn't mean to be misleading when I said I made a test light. It is an LED light I got from Radio Shack that already has power/ground wires. I have used this light on several occasions to help me diagnose various concerns with other vehicles. Most recently a Dodge Caravan that wasn't sending signal to the injectors (ironically). This isn't a typical test light used for checking fuses, etc. It works exactly the same as a noid light.
I don't think the injectors are plugged. I have never heard of all injectors in a rail getting plugged at the same time. Besides, the injectors do spray when I give them a power and ground, hence, not plugged. No, I have not done an injector volume test but since I can hear and see fuel entering the cylinder I am thinking it is supplying plenty of fuel.
Can you tell me where the pcm gets it's ground so I can check it? A wiring diagram would be awesome. For whatever reason the Chilton manual I bought has wrong color coded wires when compared to the truck I am working on. I have ran the VIN and triple checked that the truck is in fact a 1990, which it is. Thanks
Chris (aka- Moose)
Chris (aka- Moose), Technician
Category: Ford
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Experience: 16 years experience
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Customer reply replied 8 months ago
Thank you for the wiring diagram. Can you tell me where the pcm gets it's ground from?

I can see in the diagram there are 4 PCM grounds but the vehicle is to old to get a location on the chassis where they connect. You can ohm test them at the PCM and if any fail, add a new ground.

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Customer reply replied 8 months ago
Good point. I will try that this evening or tomorrow.

Super

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