Why in the world...?

[Optikalillushun]

Would u do this?
http://www.ford-trucks.com/forums/showpost.php?p=6104592&postcount=21

from a thread on FTE, it says about blocking off those two lines to cure hard starting.
http://www.ford-trucks.com/forums/636186-7-3-idi-mods.html

 

[icanfixall]

My 89 idi never had the return line connected to the filter head. I have a rubber cap over that port and the other port has the schrader valve in it. Never have had a hard starting problem.

 

[Camarogenius]

Mine isn't done that way, and it starts with no problem.

 

[93turbo_animal]

mine still looks original but the brass fitting is soiderd (sp) shut. it was like that when I bought it but what I've heard is that if you get air in your return lines the factory way will let the air back into the filter head all over but if you block it off and are getting air in your return lines it will go back to the tank and go away

 

[LCAM-01XA]

if you get air in your return lines the factory way will let the air back into the filter head all over but if you block it off and are getting air in your return lines it will go back to the tank and go away

That's what I'm thinking, their return system don't seal quite right so they just eliminated the possibility of air leak-in for the fuel filter. Now why the need for capping off the shrader valve, that's beyond me, maybe the thing is leaking on their truck?

Actually, while we're on the subject, why the need for having so many return lines on the 7.3 engine? I have one towards the tank, then another from injector #2 to the IP, and then still another from injector #1 to the fuel filter - why so many, what's the advantage over a single return line from the injectors to the tank only? I don't mind mine being like that, I have replaced my return lines and caps and o-rings and everything works awesome, but I'm curious... Ideas?

 

[Optikalillushun]

that is why i was asking, MLSC...

 

[h2odrx]

that is why i was asking, MLSC...

I would say to release any over pressure?

 

[Agnem]

The IP can flow a good bit out of the top. The little holes in the return line caps may not flow the volume needed, and could cause internal presure and alter the IP timing if the 3 lines were joined near the front. By joining it with the returns from the injector banks at the back, it reduces the presure on the IP. You can run the injector return banks together anywhere you want. I like to do it across the front. Then you have just two connections coming together at the back.

 

[LCAM-01XA]

Oh, so that line from the pump is actually for excess IP fuel? Well now that makes sense, thanks for the explanation Mel.