Several days ago my 2006 F250 6.0 started running goofy. It would not turn any RPMs any higher than 2200 and was idling rough. I changed both fuel filters and the bottom was pretty gunked up. I cleaned both bowls with carb cleaner and put new Ford filters in. Ran great for 3-4 days and put about 40 miles on it. Yesterday on the way to work it starts running just like before I changed the filters. It even died and would not start. Walked the rest of the way. Went to change the bottom filter again thinking it was restricting the flow of fuel. It still wouldnt start. Changed the top filter also. Before I put the cap back on to the top filter, I had someone turn the key on and watched the bowl fill up. LOTS of big bubbles. Did this several times and put the cap back on. Its started and only ran for about 2 minutes. Took the cap back off and turned the key back on and same thing....lots of bubbles. Run the pump until I saw zero bubbles. Tried to start it and it did start. Ran for about 2 minutes again. The bowl takes just a few second to fill. Could the fuel pump be weak and only filling the bowl when there is no pressure because the cap is off???? The pump sounds fine when the key is turned on. ANY HELP WOULD BE GREAT!!!!!!

Thanks

 

Is the tank full or less than 1/4. The footvalve in these tanks are known to have problems.

 

The tank is full.

 

I just watched the bubble test on youtube. Thats not the bubbles Im getting. My bubbles are coming up from the port at about the 12 o'clock position. Are they are big bubbles not the little ones.

 

Double check tightness and o-ring condition on lower filter cap.

 

Will do. Any chance its the fuel regulator????

 

Crazy as it sounds, it's possible to have a leak that doesn't drip fuel but will suck air. I've seen that with the lower filter cap. The regulator cover is a common leaker but it usually just makes a mess without causing running issues (sucking air).

 

Ill check the cap when I get home. Why would the truck run fine after changing the filter for 40 miles or so then die?

 

X2. If you didn't lube the oring or it was damaged it can cause as you describe.

 

Checked the cap and o ring and all looks good. Checked upper filter and o ring, looks good. I again took the cap off the upper filter bowl and cycled the key several times until very few bubbles came out. Put the filter and cap on and it started, run for a few minutes and then died. Ran to autozone and bought a airtex 2340 pump, put it in and it started right up and was run quiter than before. Ran for a few minutes and then died. Now what????? I'm stumped

 

First try this. Pull the secondary filter cap and filter. Then use the starter wire located on the passenger side of the engine compartment near the firewall to crank the engine without starting it by touching the end to the positive post of the battery. While doing this watch for bubbles coming up in the filter bowl. If there are bubbles than you have a leaking pintle or copper washer on an injector leaking. If no bubbles then try the next. HERE'S A VIDEO:
Remove the fuel supply to engine line and attach a 1/4" clear hose. Cycle the key on and watch for air. If you have air then the pump is sucking air from somewhere in the system between the pump to the tank.

 

I hooked up a clear tube and there was a lot of air. Is the HFCM bad? How are Napa fuel pumps and HFCM? About $270 for both.

 

Did you cycle the key multiple times in an attempt to purge the system? If so, and it never cleared out than the pump is sucking air. Make sure the filter is installed correctly, the lid is not cracked, oring not damaged, drain plug is tight and the line from the tank is clean and installed correctly.

Now install clear hose on the HFCM supply port and put the other end into a clean container full of diesel fuel. Leave the clear hose also on the engine supply and route that into the same jug. Cycle the key 4 or 5 times and see if you still have air. If not, the air leak is from the tank to the HFCM. If you still have air it's the HFCM.

 

Update..... Installed the new HFCM. I used the airttex pump I bought yesterday. Put it all new and ran for a few min then died. WTF???? I did purge the system before I started it. So I then hooked up a clear line to the tank side of the pump to see if it was something in the tank. Nope. Started then died. Tomorrow I'll took up a line from the pump to the tank with the new HFCM and see what happens.

 

Maybe your pulling air from the pick up tube in the tank somewhere. There are some connections that could be cracked and brittle inside the tank. Either that our you still have a leak in the connections to the new HFCM, aired pump. When you undid connectors, did they come apart properly or did you have trouble. I would also look carefully at those. These kind of things can sure be a pain.