Injectors Not Working

[Broosedamoose]

I am posting this for a friend. He has a 2005 Ranger, 4.0L, 4x4, Auto. The truck cranks but won't start because the injectors are not working. He's checked all the wiring and fuse, PATS is good, so he towed it to his mechanic and he thought it was the PCM. So he bought a new one, had it programmed and has the same issue. There is plenty of fuel pressure in the rail. If you spray it with starting fluid it will start for a second and die. We're missing something so I though maybe someone might think of something we haven't tried. Thanks!

 

[RonD]

2005 Rangers do not have PATS, Ford skipped that year, just FYI
But the cluster is "married" to the PCM, 2004-2011, so it does need to be programmed/remarried

Assuming you have fuel pressure at injectors

Injectors all get 12volts with key on.................from 1 wire, wire is just daisy chained from one injector to the next
12volt wire comes from PCM Relay and Fuse 11, but if that wasn't working then CEL(check engine light) would not come on with key on
And CEL is coming on right?

Crank sensor is working because it starts with 50/50 test, so spark is working(and you have compression)

All that's left is ground pulse at injectors, need a NOID light to test for that
Mechanic should have at least one of those?
So was it tested?

PCM has 6 ground wires and a chassis ground
pins 24, 25, 51, 76, 77, 103

 

[Broosedamoose]

Maybe it's a late 2004 because it definitely has PATS. The new PCM was married to PATS and the cluster from what he has told me. The CEL does come on when the key is turned on. According to what he has told me, his mechanic said the injectors were not receiving 12V when starting the engine. He traced all the wires back to the fuse and back to the PCM. The ground is good. For some reason the PCM is not firing the injectors. Everything else checks out ok. That is why he replaced the PCM but the problem remains! It seems something is preventing the PCM from firing the injectors. Is there anything else in the system, besides the fuse, PATS, cluster or PCM that could cause this? I feel like we're missing something.

 

[RonD]

If there is no 12volts at injectors with key on that's the problem
Or no 12v with key in START position

Just use a test light(or volt meter) on any injectors "red wire" and see if there is 12v with key on and then 12v while cranking engine, you can pull the Starter Relay in engine fuse box to test "cranking voltage" so starter motor doesn't actually crank the engine over, safer

Computer not pulsing the injectors is the ground side of each injector wire, 12volts needs to be there ALL the time or ground pulse means nothing

The 12volt doesn't come from the computer, it comes from the PCM relay, and if it wasn't working in START then there would be no spark either, since it starts with 50/50 test then PCM relay is working in ON and START


You can put a jumper wire from battery positive to any injectors Red wire, that will power all the others, and try to start
If it starts then the one 12v wire from PCM relay to injectors is bad

I think these have that large square 30+ wire connector between engine wiring harness and main truck wiring harness, thats were I would look for 12volt at injector issue first

 

[Broosedamoose]

So I decided to take some time and go help the guy. I started from scratch and confirmed it would start with starting fluid. As I was standing there running through the system in my head, I asked him if the mechanic checked the fuel cut-off switch and he said "What's that?". I'm not too sure about his mechanic and what he actually tested because that was the problem! Not sure how it tripped but he said the problem started when he was out four-wheeling with friends. I thought it took a really good hit in order for those to trip but apparently his didn't take much. I'm puzzled at how his mechanic got "plenty of fuel pressure".

 

[RonD]

Yes, the "having fuel pressure at the engine" sort of took the fuse, fuel pump relay, inertia switch and fuel pump right out of the picture on troubleshooting, lol

Good work on figuring it out

I would ask him to replace the inertia switch, with NEW not wrecking yard stuff, lol
Once they trip one time they become easier to trip again and again
Once you know where/how to reset it its fine to do, but if it trips going up or down a hill off-road.....................it can be troublesome, especially in an automatic