Ford F550 V10 6.8L does not start

YES, that could be a HUGE issue. A bad MAF can cause all manner of symptoms which could include hard starts when cold.
Mazda Skyactiv's are kinda notorious for this. Failed MAF sensor = won't start at all.
 
Mazda Skyactiv's are kinda notorious for this. Failed MAF sensor = won't start at all.
When I was troubleshooting a '14 Rogue with a fried bug in the MAF it could be REALLY difficult to start....tons of cranking and messing w the go-fast pedal. Once warm it was easier but still ran poorly of course and idled even worse
 
also I hear it could be a MAF sensor. Mine has a broken wire going into it.
Seriously? You've been looking at that broken wire for months but somehow convinced yourself that there's no way that could be the reason why it won't start?

Some basic no-start troubleshooting (after repairing any obvious broken wires etc.) is to look at all the live OBDII sensor readings both with key on and engine not turning, and then again while cranking. Consider whether they make sense. All the temperatures should be around the ambient temperature. The rpm must not be zero while cranking. The MAF should start near zero and increase while cranking.
 
Last edited:
My nephew bought my 2010 Ford Crown Victoria from me and had intermittent no start issues.

My scan tool tells me fuel pressure in the live data stream and showed very low, 5 psi pressure. It would build up and then start.

Fuel tank was rotted out on the bottom of the tank. On that car, the seam of the tank is down in the mess under the car and has rubber mounts that hold the water, salt and other crud to rot it out. Leaky tank, losing pressure. Replaced it with a salvage tank so all fixed?

Nope. That solved retaining fuel pressure. But another problem was the failing fuel pump relay. It would work for a time, then stop. Work, then not work. Replaced that for a couple dollars and it’s flawless.

The tank and hacked up fuel pump needed replacement but the relay was the final piece to fix it like near new.

The tank and hacked up wiring on the old fuel pump attached.
 

Attachments

  • IMG_0166.jpeg
    IMG_0166.jpeg
    206.7 KB · Views: 10
  • IMG_0167.jpeg
    IMG_0167.jpeg
    187.9 KB · Views: 10
  • IMG_0168.jpeg
    IMG_0168.jpeg
    193.3 KB · Views: 10
  • 68633244774__3A473780-8B96-4142-91C5-AE982540F8BF.jpeg
    68633244774__3A473780-8B96-4142-91C5-AE982540F8BF.jpeg
    227.3 KB · Views: 10
MAF sensor has been replaced, its code went away.
The Intake Air Temp sensor code also went away, right now I am getting no codes at all via Forscan and was able to confirm it with an Actron scanner.
Crank, camshaft pos sensors all pass. Watching in real time. All 10 injectors pass, show no fault.
Ran the Key-on-engine-off test in Forscan, nothing found.

And it still does not start.

Have a Ford guy on site, he thinks the injectors are not grounded by the computer, he checked the pulse. It's getting spark but no pulse. This is getting too esoteric for me. He sampled some gas, does not think it's the gas anymore.

How likely that it is the computer itself? Or some ground wire?

the most weird thing is, he unplugged the coil and an injector and these did not show up in either Actron or Forscan. Even after cranking and even when looking at live data.
What does that mean?
 
Does the MAF reading make sense? It should be near zero with engine not turning, and increase while cranking. Also of course the IAT should be about what the outside temperature is.

Quit thinking in terms of codes and look at live data.

Would be good to check if the injectors have power on the side that is not connected to the PCM. There may be some other dodgy wiring.
 
Have a Ford guy on site, he thinks the injectors are not grounded by the computer, he checked the pulse. It's getting spark but no pulse. This is getting too esoteric for me. He sampled some gas, does not think it's the gas anymore.

How likely that it is the computer itself? Or some ground wire?

the most weird thing is, he unplugged the coil and an injector and these did not show up in either Actron or Forscan. Even after cranking and even when looking at live data.
What does that mean?
PCM is always the last resort. It can happen but I'd be leary of jumping onto that diag.

If you have the patience I like this guy and he runs through testing of the coil drivers. You should be able to do the same with Forscan and a test light.

There is a point in the vid where he concludes the PCM is bad and if you can't replicate similar results, I'd be suspicious.



Nothing worse than replacing a PCM and still not fixing the problem.

Also the vid was a severe misfire but the car still ran. And I haven't even searched for vids about the V10 which obviously might be more relevant
 
Back
Top