vapor seperator.. do i need it?

[challngd73]

Ok, I had a thread re: a fuel pressure problem caused by my return line from my fuel injuection, apparently the blockage is the vapor seperator.  Do I need this or can I bypass it and run the return line directly to one of the 4 lines this was connected to?   If I can, does it matter what line I run it to?  What do I do with the other lines, cap them or leave them open?  Sorry for all the questions, this is the last thing holding us up..

[burdar]

There is a valve in the separator.  The valve is in the nipple that connects to the vapor line....not in the four lines going to the tank.  If you are using that vapor line as a return line, the valve in the separator will block fuel flow.

To answer your question, YES you need the separator.  If you fill up on a hot day, the fuel is going to expand.  It needs somewhere to go.   That is one of the jobs of the separator.  Its other job is to let fuel vapors travel to the charcole canister in the engine compartment.  The fuel vapors are stored there so they can be burned...instead of being vented into the atmosphere.
   
Here's what I'd do...

If you are using the 1/4" vapor line as the return, I'd dissconnect it from the separator and run it into the fuel filler tube.(that way you don't have to have a nipple installed in the fuel tank...you can have one installed in the filler tube)  Then you  need to run another vapor line off of the separator.  Route it so the end of the line is higher then the fuel tank.  I'd put a fuel filter or something on the end of it so you don't get any junk down inside the line.

Another option is to run a separate return line but still have it empty into the fill tube.  That way you would still have the factory emissions system funtional.  It doesn't cost any HP so there's really no reason to remove it.  If you have already tossed the charcole canister, you could run the vapor line into a valve cover breather.

[Aussie Challenger]

If you have already tossed the charcole canister, you could run the vapor line into a valve cover breather.

No, Never, do not plumb fuel or vapor into the engine valve covers, back to the tank is best.   

[burdar]

In 1970 with ECS and in 71 the vapors were just routed to a valve cover breather.  They didn't start using a charcoal canister until 72. 

You can't run the vapor line right back to the tank.  That would be like just plugging the line all together.  As the fuel is used from the tank, air has to get back into the tank or it will build a vacuum.

If you don't want to run the line to a breather, you'll just have to let it vent into the atmosphere.  In 1970 with NON ECS, the tank was just vented into the frame rail.