I've been dealing with some debris from my tank for the last year and finally have the time and cash to get a tank, sending unit, and new fuel lines. Currently the aux tank doesn't work. I only run on the rear tank which I assume is an EEC tank, but I don't think everything is hooked up. The blue canister in the engine compartment has a line going back to the tank but that's it. Nothing going to the air cleaner, which was replaced with an aftermarket part by the previous owner. I'm assuming the line from the canister connects to both tanks somehow. Obviously the previous owner removed some EEC component(s) as both gas caps are vented, which I thought was only required for non EEC systems. I haven't dropped the tank but judging from the presence of the line running back from the canister, and the tank breather line being in front of the filler neck instead of behind it, I think it's safe to assume it is EEC. I can't find a tank locally so I'll have to have one shipped and I'd like to have it on hand when I drop the tank.

So, basically the EEC stuff isn't hooked up. Maybe there was a problem in the past and the PO switched to vented gas caps to "fix" it? Dunno. Regardless, should I go through the hassle of trying to sort it all out at this point, or get a non EEC tank and be done with it. Truck runs great at this point.

My goal is to keep the truck running for a daily driver. I don't wan't to do anything that will make unnecessary work for me in the future or hamper performance. I am planning on getting a 4bbl intake and carb soonish, probably edlebrock 1406. Currently I have a 2150. Not sure if the edlebrock is the best choice. I don't really care that much that the aux tank isn't working right now, but I would love to have it working eventually.

.....

Well, as per usual, writing this all out my have answered my question, but I'd welcome any advice.

 

If it were me, I'd hook up the canister purge system, since you have the tank and canister. Will prevent any gassy smell on hot days, and be good for the environment besides. There really aren't any performance penalties to having or not having it. Does your truck have EGR? The vacuum systems for both are often tied together; if the PO deleted EGR, that could be why he deleted canister purge too.

If you want to hook it up, here's what you'll need to do:

Run a line from the emissions vacuum port on the carb (see below) through a ported vacuum switch (~100°F), and a vacuum delay orifice, to the control port on a canister purge valve. The flow ports of the canister purge valve should go to the canister on one end, and tee into the PCV line on the other. The fuel bowl vent on the carb (if equipped) should go through a bowl vent solenoid (wired to something that's hot in run or run/start) to the canister also.



If it's helpful, here's a vacuum diagram I put together for the 4 bbl system I'm putting together for my truck. I'm using a Holley 4180C from a mid-80s Mustang or truck and plumbing it up like this (the dual canisters were something Ford did on the factory 4 bbl applications, at least in the Mustang; if you were doing your own with the one factory canister, you could tee the two fuel bowl vent lines together between the canister and the solenoids).

 

Evap/Em = Evaporative Emission System

EEC = Electronic Engine Control (on board computer). Only 1970's vehicle to have it: 1979 LTD/Grand Marquis 351W

 

ND: EEC is also widely used (even if not in Ford parts manuals) as an acronym for Evaporative Emissions Control, which is what he was clearly referring to. If you shop for gas tanks, that's the term that will pop up, e.g. Truck Parts and Truck Accessories

 

Also, if you don't want to go to the trouble of getting your evap system working, you could just plug the vent line from the tank and remove the canister, since you've got a vented cap. If you get the evaporative emissions system working, you'll want to switch to the correct gas cap, of course.

 

bkaul: Thank you for such a thorough explanation of how this all should fit together. I do still have an ERG. I am going to get the correct tank for Evaporative Emissions Control and keep things hooked up as is for now, though I may disconnect and plug the line from tank at the canister since it's apparently not doing anything right now. But I'll leave it in place in case I start to notice any fuel delivery problems. Once I get the 4bbl set up I'll revisit this thread and may ask you more question. Expect that in, I dunno, 6 months? haha

 

EGR (Exhaust Gas Recirculation) Valve bolts to the EGR/Carb spacer plate. It has nothing to do with Evap/Em.

 

Thank you ND, for your reply. I use ERG in my job and wrote it out of habit. I only mention it because I was asked if I still had one, and the carb evap port is connected to it.

 

The canister purge isn't related to the EGR valve per se, but they use the same vacuum source to control them so many POs rip them out together.

If you tee off the vacuum line going to your EGR valve to control any canister purge system you install in the future, that should work.