So....I am losing vaccum to my IWE's so I decided to change my check valves and run new lines. So, I took off my air filter box so I could get to the lines that run behind that. As I was pulling off the first check valve, I pulled the red vaccum line from behind the air box. I tried to find out where it came from, but I had no luck. Anyone know how this goes back together??

Here is a picture of the line I pulled out. And it goes behind the air box and down, and I cant get at it!!!

 

For some reason I cant post a pic, but its the hose after the last check valve and it goes behind the air box and attached somewhere behind that?

 

Have you looked at this thread yet? There are some instructions and diagrams. I have never done the vacuum lines but I did do both iwe actuators. Hope this helps!
https://www.f150online.com/forums/sh...d.php?t=371618

 

Well I took my truck to ford. 8 mins and $62 later, the guy told me he couldnt get his hands back there to get the line back on, so I need to pull off the intake to get at it. He said they would charge $750 to do the job, but im going to do it myself.

I think if I take off the fuel injectors/rail I should be able to get at it and push it back on. Hopefully this solves my 4x4 from grinding under engine load. I have replaced everything on the system (new lines, check valves, vacuum box, solenoid, IWE's), so this is my last resort

 

Try reaching from the bottom, over the top of the transmission. I was able to reach the vac line that goes to the brake booster that way. Worth a shot.