7.3 fuel flow on return lines

[Willie Two]

Can someone help me to understand the purpose of the line pressure sensor attached to the # 1 cyl. injector, how it works. and why we need it ? Also how far into the tank (s) does the return line (s) go, is it just sitting at the top ? I want to be sure these lines are clear and working properly so I am thinking of sending some compressed air down the line from the rear T fitting. Thanks to all who reply.

 

[suv7734]

The unit you're talking about on the #1 line is the 'connection' for timing the engine, it is not a pressure sensor. I'm not sure on how the return lines enter the tanks. If you apply compressed air to check return lines don't apply more than about 10 PSI. The return system is relatively low pressure and as such the connections are not rated for full shop air pressure.

 

[f-two-fiddy]

The return lines exit at the left (drivers side) rear of the engine, down to the tank select switch, then to the proper tank. They have very little pressure on them. The lines enter the tanks at the sending unit. Each sending unit has two hard lines with fuel connex, one for the fuel supply, one for the fuel return.

 

[Agnem]

You cannot remove the timing sensor. If you were to do that (and I've seen it done), the line will fit like crap, and be shorter than the rest, adversely affecting the timing on that cylinder. If you really want to get rid of it, find either a #1 injection line off of a 6.9, or get a #1 injection line from a 7.3 in an E series, which has the pulse adapter on #4.

 

[Willie Two]

Thanks for the info . I really appreciate the help.

 

[icanfixall]

Willie.. The return line is about half way down in the tanks. Its 5/16 inch and has a non return baffel kinda like is found on the bilge drains to a small boat. As fuel is being pushed thru it the system works but it wont flow the other direction. Hope this helps you to understand what things look like.

 

[Willie Two]

Check valve

And the return line going from the fuel filter to the # 1 injector cap has a check valve at the fuel filter, mine is missing, does it play an important roll with respect to the air bubble bleed ?? I still have the barbed fitting with the orifice size hole just no check ball. I am assumming the fuel flows from the filter to the injector cap but not the other way ???