6.9 idi air intrusion!!!

[The_gestach]

The first picture is a picture of my fuel cap I’m wondering if since the cap has no vent on it could that be an issue? Also the other photos are the lines inside of the engine bay

 

[The_gestach]

This is my bypass for the water separator.

 

[The_gestach]

This is my electric fuel pump from orileys it goes back over the frame into the steel line that runs by the transmission the only 2 lines that I haven’t replaced are the steel line that go next to the tranny and then the line that goes from water separator to where the mechanical pump use to be

 

[Farmer Rock]

There should be a vent hose on the fuel tank(s). You can try running it without the cap, but it doesn't really sound like a venting issue. Those 2 steel lines are the 2 that gave me trouble. Very hard to see pinholes on those lines.


Rock

 

[OlKoot]

i used those pumps, the green electric ones, but ended up back with a mechanical lift pump. Indestructable, and only 26$ roughly. Made a big difference. the electrical ones, only work when pushing and will suck air into the fuel if up to far from the tark. sucking air, in through he bass ends as air is lighter than fuel

 

[ROCK HARVEY]

It looks like you’ve still got an olive seal in your system that may be causing air intrusion. The steel return line coming from your IP towards your transmission(badly circled in this photo) has a 3-way fitting on the back end that has an olive seal in it. Olkoot posted a great photo of the return line and fitting. I marked the nut with the olive under it. Making temporary ones out of hose will work in a pinch, but fuel hose is only impervious to fuel on the inside, the outside is a different material so it won’t last as long as an olive. You can get the non-viton ones from lots of places, even Amazon under “fuel line sleeves”. I still think the “jug of fuel” test would be a good idea, and I would definitely put a cheap inline fuel filter before your fuel pump, even if it’s only temporary. Good luck!

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[OlKoot]

Thats it, what i did was i removed i, and adjusted the position of the line, and then tightened it. After lubing the line under the olive seal. Making sure it was tight

 

[The_gestach]

So the return line can also cause this air intrusion that’s coming through the pump going back to the tank? Because when I see the bubbles they are existing the pump return fitting. Never have I seen bubbles coming up the return line. The arrow on the photo I have attached is the way I see the bubbles. Some times the return line doesn’t stay full of fuel some times it’s completely empty I kinda forgot to say something about that too.

 

[ROCK HARVEY]

Air intrusion in your return system will cause hard starting because all the fuel will drain back to the tanks while the truck sits, then it has to get all the way back up before the engine can start. Kind of like how if you have a drink with a straw, you can put your thumb on the top of the straw and lift it up and it will stay full of liquid, but as soon as you lift your thumb and unseal the top (air intrusion), all the liquid drains out.

Air coming out of the IP return while the engine’s running is a different story. There’s gotta be a hole or a clog somewhere between the tank and the IP, unless that electric pump just isn’t pushing enough fuel. Those are the only possibilities I can think of anyway.

 

[Farmer Rock]

Air intrusion in your return system will cause hard starting because all the fuel will drain back to the tanks while the truck sits, then it has to get all the way back up before the engine can start. Kind of like how if you have a drink with a straw, you can put your thumb on the top of the straw and lift it up and it will stay full of liquid, but as soon as you lift your thumb and unseal the top (air intrusion), all the liquid drains out.

Air coming out of the IP return while the engine’s running is a different story. There’s gotta be a hole or a clog somewhere between the tank and the IP, unless that electric pump just isn’t pushing enough fuel. Those are the only possibilities I can think of anyway.

Air intrusion in the return system shouldn't cause hard starting since it's after the injectors, but will just cause the motor to surge and lope. Hard starting is air intrusion in the supply system.


Those smalls e pumps seem to have trouble pulling fuel up out of the tank.



Rock

 

[TNBrett]

Air intrusion in the return system shouldn't cause hard starting since it's after the injectors, but will just cause the motor to surge and lope. Hard starting is air intrusion in the supply system.


Those smalls e pumps seem to have trouble pulling fuel up out of the tank.



Rock

I think you have that backwards.

 

[OlKoot]

There is so much prssure being built up in the pump, any place air can get insideitwill. Even backwards up past the fuel coming out, because air s lighter than fuel

 

[Farmer Rock]

I think you have that backwards.

Hard starting would be more of a drain back problem, there's not really any way for a return line leak to back feed air through the IP/injectors, and cause the fuel supply to lose pressure. I suppose the return line on the fuel filter could though.


Rock

 

[OlKoot]

I had issues, wth that little green fuel pump and went back to the mechanical pump, no problemsn no more. And, we used to at Ford, install back flow preventors below the fitting at the rear of the return fule line, to keep pressure in the system, and air out. Some moore than one n the return line

 

[ROCK HARVEY]

Hard starting would be more of a drain back problem, there's not really any way for a return line leak to back feed air through the IP/injectors, and cause the fuel supply to lose pressure. I suppose the return line on the fuel filter could though.


Rock

I see what you mean, since he deleted the fuel filter housing and return line.