Is there a source of pictures, diagrams, or other info to help locate potential points of wiring chafing that causes my intermittent no-start?

 

Oops, I just found Bizmic's post on the No Start Tech folder.

 

Is the truck being a bugger again?

I think it needs to treat you better after all
the work you have put in to it.

I screwed up and ended up having to put the
same injector in twice. Bad torque wrench caused it.


Anyway on you problem also look for mushy spots in the harness.


Sean

 

To me their whole engine harness system is one big chafe point. Routed poorly;secured in the wrong places and not enough slack between secure points.
Just my opinion of course.

 

This is a crazy truck, the way it'll stop out of the blue and then start as if nothing was wrong.

I got under the hood and just started tugging on the harnesses wherever I could get my hand on it. Got back in and it fired right up. Pretty sure I got a short somewhere - my guess is the driver's side under the turbo intake, near the FICM, etc., from me taking it apart so many times.

Which wire would make it not start, make it not show any FPW, yet let all the other readings seem normal, and then, when the chafe moves and the short clears, it runs fine for weeks?

I'll get into it tomorrow and figure it out.

stay tuned and thanks for the help.

 

Set you SGII to read Vref and put it so you can see the display and start tugging.
When it drops out you are near the right spot.

The other way needs you to un hook almost everything and then check each wire
one at a time at both ends with a continuity tester that has a tone so you can hear
when you find a break. Both of these are a pain in the *** to do and take a lot of time.
But if you look at things and see there are places that can be more prone to problems
than other places. Places that make sharp bends of that are covered with oil.

I agree with what Dannyboy has to say. The harness could of used a bit more thought
before they put it into production.




Sean

 

Great, thanks. You know I hate electronics, but I can look at a gauge and tug while chewing gum. Whenever I've looked at Vref, it's always 5.0. Even when it wasn't starting. Now, I've apparently tugged it away from the short, so you're saying that when I push it back to where it shorts, Vref will drop? Cool, I can do that. Hope it works, stay tuned!

 

Things started to go downhill almost two decades ago when the brilliant idea of cost savings by minimizing copper wire length and diameter swept through all manufacturers design teams. Unfortunately it is still happening as there is one Ford platform out there that has a ridiculous amount of harness issues, more then the 6.0l had.

 

Just keep in mind that you could have something else doing it.

Have you rechecked the FICM plugs? if one of them pops off you get a no run.
But one would think that might set a CEL. Have you scanned it right after it died?
If you don't have any codes then we can start looking for things that can cause a
no code no run condition.


You have to tell us what one it is.


Sean

 

They call that the Shake Test You might have to opt out and just replace the harness if you do not find the rub spot.

 

Which one is that?

 

There is a large bundle of wires going across the top of the drivers side shock bolt wrapped in tinfoil wrap on mine (2005). I put a shock bushing on top of the bolt on mine(the bundle is resting on the bushing now) when I changed my shocks as this wire wrap was rubbing, touching the top shock bolt. If this outside wrap is broken this is a likely spot for problems. The whole bundle is atleast an inch plus thick, many many wires.

 

I had to make a stud mount for the harness that goes around the front
driver side valve cover. The plastic from the original had cracked and fallen
away. I took a small rubber hose and did a little creative trimming and it
works just find now.


Sean

 

Focus comes to mind.

 

Darn I was thinking that little baby mercury cant remember its name.