Fuel return line siphoning fuel?

[turboman1]

Is it possible if there is a pin hole somewhere in the supply line (post fuel pump) for the return line to siphon the fuel out of the fuel filter (since there is about a 2 foot drop back to the tank) via the line that runs directly into the return system. The one I am referring to is the one with wire sheathing around it.

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Thanks
Adam

 

[icanfixall]

No. That can't suck fuel out of the system but it can allow air to be sucked back into the filter if the leak is down the line from the filter but above the lift pump. The lift pump has a built in check valve. Now if the lift pump check valve goes bad your going to suck air back from the filter draining it.

 

[yARIC008]

You can get a little inline filter/check valve to install to prevent this if you suspect that's the problem, they're on ebay and amazon.

 

[Agnem]

You most likely need to re-do your return lines. Our fuel system is like a soda straw. Put it in a full glass and cover the end with your finger, and you can take that straw out and it will hold all the fluid in there. Take your finger off or let just a tiny bit of air in there, and it's all coming out. Same principle. You need an air tight return line system and right now, you don't have one.

 

[icanfixall]

Thats a very good explanation Mel. I'm looking at the posters pics and the return caps appear to be grey but the lines are not. Might be a cobbled return line system too thats developed a small air leak. Probably a good time to replace the return line kit...

 

[turboman1]

I actually had to pull the entire fuel system bc the fuel gelled in it and ruined the injection pump...stuck in all the lines and tanks too. Cleaned the tanks, injectors, fuel tank selector valve, and installed all new lines from tank to lift pump (installed new IP too). The IP supply lines were put in some rust remover and then cleaned with brake cleaner so all of the paint got stripped off (just haven't got around to painting it...needed to get the truck running to take through emissions). After initial start up I had a little leak coming out of the water in fuel sensor on the top of the filter housing but somehow it cured itself. I think there could be a small pin hole leak up there that once shut off allows the fuel to drain through the return line. Plan to install a inline check valve as mentioned above and see if that works.

Thanks for the replies

Adam

 

[icanfixall]

The water in fuel sender is found in the bottom of the fuel filters on the 7.3 engines and not on top. That electrical fitting on th top is the fuel heater. It has an o ring that leaks. International sells the o ring for $2.50 each. The part number is in the PARTS BIN section of this forum. Buy 2 of them. they are cheap. That leak didn't go away. It just seems like it did but its sucking air which is a smaller molecule than a fuel molecule.

 

[turboman1]

Gotcha...makes sense and thanks for the reply

Adam