I have an 87 F250 NA 6.9L automatic. I was having air intrusion issues so I checked the fuel/water separator it was already bypassed, so I got an electric fuel pump and took out the mechanical blocked the hole with a part from Napa. Eliminated the fuel return line to the fuel filter. The problem is I still have air intrusion. The fuel tank is at 7/8ths of a tank, I pulled the outlet line off the electric fuel pump and I am still getting air in the fuel. I replaced all the soft fuel lines with diesel fuel line. I am not sure what I should do next. I have not messed with fuel tank selector valve yet, not sure if I should or not. I don't know where to get the right valve. The one Napa sells is slightly different in the location of the ports and the electrical connector. If someone has had this problem and knows of an answer I would like to hear it. Pictures would be a great help too......Thanks for all the help, I am starting to lose my mind and I really don't have much to spare.

 

I've seen the hose connections at the tank suck air before, but I don't know where to get new gaskets.

 

where did you place the electric fuel pump?

 

Here's a little more info. replaced injectors and fuel return lines last year. the electric pump is located near the alternator.

 

temporally install the pump near the tank, and see ware the leak is.

 

Did you add clear hose to see if are is going into and out of epump? I have the same problem but
Speedwrench says it could be Glow plugs . I have manual GP plug button. I will check my relay this weekend. Also if you have a block heater plug it up if it start warm then its glow plugs that's what i was told. I intend to add a inline block heater soon because mine i blocked.

 

My truck will start but dies within a few seconds. then air at the schrader valve on the filter. I will check glow plugs but I don't see how they would put air into the incoming fuel line. I am thinking I might just replace all the fuel lines with new line. should I bypass the fuel tank selector valve since it doesn't work right now anyway? Any thoughts or help would be appreciated.

 

I thought i had air coming in from tank, FSV or Water separator . You can get clear line from home depot cheap. You may want to check your Fuel Olive do a seacrh for more info on that mine was Bad. I included a pic of it.

 

OK here's an update I believe I have the air intrusion issue under control however my glow plug controller doesn't seem to be working. The truck would crank but not turn over. I am going to replace the controller but I am wondering if that is the problem as it was 100 degrees here today. Does this seem like it could be the problem? I need some ideas here.....I really need the truck running ASAP.

 

OK replaced glow plug controller....no joy.....ran new fuel line from the tank to the new electric pump, checked for fuel, had PLENTY of fuel. So after some cranking.....ok after a lot of cranking......she fired up. I see some seepage from a couple of injectors but she runs. Woo Hoo. So it turned out to be the fuel tank selector valve. I am going to pull it at a later date and rebuild it, but that is for another day. Thanks to all of you on here.....You guys rock!

 

OK I let it sit for like an hour or so and it doesn't want to start.....WTF? I am really lost here. the electric fuel pump is supplying fuel, glow plugs working, It ran for 45 mins with no issues now I am a hard/no start.....Batteries were low so charging them know. Do I need to bypass the return line from the fuel tank selector valve also? Please help. Ugh.

 

If its not air, its the IP. Try pouring some water on top of the IP to cool it off then crank. If it starts, time for a new IP.

 

I've had injectors stick and act like an air intrusion, they stick so that they just push all the fuel into the return lines.

 

Does it restart if you turn it off then restart right after that ?

 

Yes it acted just like a dying injection pump, it would restart right away. let it sit 30min it wouldn't start. It would also die right after starting cold if you didn't hold the rpms up.