Fuel injector problem
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Joined: Jul 2009
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Fuel injector problem
Hello, I am new on here. I have a 2001 F250 5.4 with 85000 miles. The problem I have is it started missing the other day. Took to my mech. and he said #5 cyl. misfire. So he change all plugs and coil on #5. That didn't help. Then he ran some more test and said the injector was not working. He switched out between cyl. and found that #5 injector wire was not getting any juice. He said I needed new ecm. So yesterday I had the ecm replaced. Still does not work. Does/has anyone else have this problem?
Thanks 2k84
Thanks 2k84
Elder User
Joined: Nov 2008
Posts: 668
Likes: 6
From: Northfield, MI
The injector circuits are very simple. One pin at the injector connector gets supplied with battery voltage from the PCM relay whenever the key is in the "ON" position. The other pin gets grounded by the PCM to turn the injector on.
Since all the injectors are fed from the PCM relay, you either have an open circuit from the point that the wire harness splits to feed each injector, or you have an open circuit from the injector to the PCM.
These checks should have been done long before any parts were replaced, and it takes literally less than a minute to check the injector circuits at the injector connector. After that, a few more minutes with a DVOM will find the problem.
Since all the injectors are fed from the PCM relay, you either have an open circuit from the point that the wire harness splits to feed each injector, or you have an open circuit from the injector to the PCM.
These checks should have been done long before any parts were replaced, and it takes literally less than a minute to check the injector circuits at the injector connector. After that, a few more minutes with a DVOM will find the problem.
Posting Guru
Joined: Mar 2007
Posts: 1,191
Likes: 1
The injector circuits are very simple. One pin at the injector connector gets supplied with battery voltage from the PCM relay whenever the key is in the "ON" position. The other pin gets grounded by the PCM to turn the injector on.
Since all the injectors are fed from the PCM relay, you either have an open circuit from the point that the wire harness splits to feed each injector, or you have an open circuit from the injector to the PCM.
These checks should have been done long before any parts were replaced, and it takes literally less than a minute to check the injector circuits at the injector connector. After that, a few more minutes with a DVOM will find the problem.
Since all the injectors are fed from the PCM relay, you either have an open circuit from the point that the wire harness splits to feed each injector, or you have an open circuit from the injector to the PCM.
These checks should have been done long before any parts were replaced, and it takes literally less than a minute to check the injector circuits at the injector connector. After that, a few more minutes with a DVOM will find the problem.
Post Fiend
Joined: May 2006
Posts: 10,007
Likes: 4
From: Central Florida
Did the diagnostic software show a bad injector/injector wiring?
A simple test just to verify, the switched wire (orange I think) will show AC voltage if it's working. The strobing of the ground will read kind of like AC voltage and a DMM should show ~5vac at idle and more voltage as the RPMs increase.
A simple test just to verify, the switched wire (orange I think) will show AC voltage if it's working. The strobing of the ground will read kind of like AC voltage and a DMM should show ~5vac at idle and more voltage as the RPMs increase.
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