Good day, I just read your issue that you had months ago. I am having what sound to be a very similar issue with my 2003 6.0L F350 Dually.
I am very curious to hear what you finally figured out to solve the Air getting into the Fuel System!!!!
Please respond with the details when you have time.
The Following are the details of my issue if you care to read.
Thanks Scott 561-598-9900 if you care to chat!!
I have a 2003 F350 6.0L Dully that will start up idle and then upon driving any faster than 20mph (about 1 mile) it will get air into the system. Once that happens I must stop, park and cycle the ignition 3 0r 4 times to get the air back out of Filter Bowl to then re-start and drive back to house.
List of parts replaced to attempt fixing this Problem:
Main Frame Fuel Pump, Pressure Regulator Upgrade Kit
The Secondary Filter Housing is getting air into it from the Large Bottom Line to the left when looking down over the housing. Bubbles will come out of this line and the Fuel level will drain down to about 1/4 full.
1) Is it possible that this is a internal Injector Sealing Ring or Cylinder head Passage Leak????
2) Or is this most likely a striction issue that the Frame Pump is sucking air into the system every time it is cycled???
3) Or some other simple fix that I have not been able to think of??
Anyone that can help will make my day.
I could attempt to drive the Truck back to the Ford Mechanic for him to install Gauges on the System to find the Leak. The only issue with that is I feel that I could cause injector damage getting it to him.
Thanks Scott (Very frustrated at this Point)
Any advise would be great at this point. 561-598-9900
Long Detailed version Below if you car to read.
I Had a Certified Ford Mechanic replace the Main Fuel Lift Pump on the Frame. (Complete housing and New Ford Filter Assy with Cap)
He said that the pick up in the Tank most likely was broken and was causing the Striction in the supply to the old pump, thus caused it to fail.
I filled the tank up after I picked it up with the new Pump installed and got about halfway home (About 6 miles) before it started acting the same way as described above. I was able to limp it home buy stopping several times and cycling the ignition. I then let the truck set for a few weeks.
2) The Mechanic did not replace the Secondary Fuel Filter during the replacement of the Pump. So I decided to replace it myself.
So I took the cap off and noticed that and old filter was dry and not a drop of fuel was in the Pressure regulator housing.
I cycled the ignition with the cap and filter out 2 times before I starting seeing fuel. Once the fuel was to the top of housing key off I looked for Bubbles and drain back. Many bubbles were present and the level drained back to about 1/4 full. I repeated this 3 times before installing the new Filter and snugged the cap in place.
I started the Truck let it idle until it sounded smooth. Then attempted to drive it and had the same Original issue of what I am Assuming is Striction in the Fuel Supply to the Frame Pump.
3) Days later I cleaned the Fuel Grime off the Secondary Filter Housing with Brake clean and started her back up to check for any leaks around the Pressure Regulator manifold and fuel/line fiittings. I found that Bubbles were present at the Gasket flange area of the Pressure Regulator Manifold.
I hoped this was my source of the air leak. I bought the Fuel Pressure Update kit from Ford and installed it. Before putting the Filter back in the Housing I cycled the Ignition many times to fill the filter Housing. I noticed once it was full that Bubbles would come out of the Large Bottom Line (the farthest Left one looking down at the Filter Housing). This troubled me.
I Put the filter back in and snugged the cap. Then cycled the Ignition 3 times and started it up. it ran quite rough at first so I shut it off and cycled Ignition a few more times and started it again. This time it seam to clear the air out of injectors and finally idled smooth. Took it for a drive and the same thing happed with air in the system. This time I could drive real slow and get back home without stopping several times.
I did have a couple of injectors replaced over a year ago. I will try to call the Mechanic that did it and ask him witch ones if that would help any.
Thank You to anyone that can offer some insight to help me fix this Truck!!!