7.3L Fuel filter head question

[Fordman75]

This is probably a stupid question. But I'm still learning about these IDI's.

I'm going to be replacing my entire fuel system on my 91 7.3L except the filter head and the injector hard lines.

I was looking at the filter head yesterday and I noticed a return line goes to the filter head. Can someone tell me why? What is the purpose? Is there some kind of check valve or something in the filter head? I've been searching but can't find anything about it.

I want to modify my system so I can basically add a second separate fuel system (except for the IP & injectors ) for WMO. I want to run a couple electric 3 way valves (one in the feed and one in the return line ) . This will allow me to start on straight diesel and purge the system before I shut it off.

 

[GenLightening]

I believe it's there to help purge the air from the filter to the return system. Some (me included) have deleted it with no issues.

 

[Fordman75]

Cool, that is good to know! Thanks.

 

[Brianedwardss]

Yes it's there to purge air from the filter, and 7.3L's have a check valve as well. The nipple that the return line is clamped to on the filter head is the check valve, it unscrews easily with a small wrench on the hex part of it. It's a very small brass piece that looks like an ordinary fitting, except ford charges $25 for it

 

[LOGANSTANFORTH]

If this was bad would it cause air to back up in the filter and not go through the system???