Alright, so i was talking to Fastlane about my fuel system problems in his build thread, and thought i would start a new discussion rather than hijack his thread any further. Here's the conversation.

Quote Originally Posted by Fastlane View Post
Using the 87-93 Fuel Injection Lines on the LTD are a different story, I first attempted to bend the old lines to fit, but it needed several bends and once done it looked like crap, so I ended up purchasing some new 5/16 and 1/4 line along with some tools to bend and cut the lines . This was a learning experience so I ended up wasting several feet, but the Tube is cheap (25 feet is around 25-30 dollars).
I did use some of the Original Fuel Injection tubing, but only to where goes under the fender and connects underneath near the sub frame, from there I used new tubing. To connect the old and new tubing together I used a "Fuel line Compression Union", which worked fine, no leak issues at all. Just make sure if you use these that they are made for fuel. This type of Compression fitting it all brass, so the fuel wont break it down and cause it to leak.
https://www.amazon.com/Dorman-800-22...n+800-222+Fuel

I may end up replacing with Stainless steel Flex line, but this works fine for now.
Quote Originally Posted by ZephyrEFI View Post
Interesting. I scrapped the Mustang fuel line as well and went to -6 braided stainless. I'm not sure if that's too big or what, but I've never been able to get my fuel system to work well. The fuel pressure always drains back after i shut the engine off, despite going through several fuel pumps and regulators. I'm pretty sure the problem is on the pump side, so i have yet another pump waiting to go in. I just hate pulling the gas tank. I also have a vapor pressure build-up problem. I can't pump gas into the thing without it spitting back at me. SO frustrating. I know i need to fix it; I'd rather not blow up if I can help it.
Quote Originally Posted by Fastlane View Post
In my case the only thing wrong was an old pump I used. Once the engine was shut off, the pressure drop right away. The new pump holds the fuel pressure for several hours after the engine is shut off, which is what it should do.

Will the LTD LX Fuel Tank Fit into the Zephyr? Its a 20 gallon tank, but comes with the correct Vapor Valve which connects to the Vapor Canister and the fuel pump sits in the tank like the mustang. The Vapor Valve I believe is what keeps the fuel pressure stable, and if its not part of the fuel system this may be what is causing the problem with the Zephyr.
Actually I do have an LTD tank in my Zeph. It's from a wagon because those are the same as '78-81 F/Z and Granada/Cougar tanks just with the provision for the in-tank pump. Later F/Zs, and LTD/Marquis sedans went to a "deep well trunk" and used a different tank. I retrofit the high pressure pump onto the low pressure LTD pump hanger, much the same way I'm sure you did.

The vapor valve is there, and brand new. the vapor line going to the engine bay is mostly new. All the seals on the tank are new. THE TANK ITSELF IS NEW! The only things that aren't new are the filler neck, which is not available new, and the carbon canister and purge solenoid/valve.

I could buy a new carbon canister and solenoid, but that's almost $100 and I've blown so damn much money on this so far with no result. And the solenoid does not throw a code.

That said, the tank vapor valve being new does not guarantee it works (my fuel pump roulette has taught me that), i suppose. But i don't really know how to test it. I tried blowing into it, but that didn't do anything. I know it's not the gas cap, since i have the symptom (gas spitting back at me) when the cap is off. I suppose one possibility is the air passage in the filler neck. I can't say with absolute certainty it's clear (although i don't see how i could have missed that).

I'm hesitant to go to the trouble of pulling the tank because of the possibility I'll put it back together again and it still won't be fixed. That would be a HUGE letdown.

Any ideas?