I'm confused. My OE cap should allow air in when vacuum builds but the tank was vented to the charcaol canister.

So this cap LINK is listed for a 72 Cuda, and states it's an Emissions fuel cap? ... but what does that mean? It also says "the caps can have two different breathing systems: vented or non-vented" and "In order to reduce air pollution as much as possible Gates supplies a special ecological cap. It is fitted with a venting valve system which prevents evaporation of harmful car fuel gases and complies with the EEC directive No. 70/221. In case of an accident the safety valve prevents fuel leaking from the tank."

The "vent" should be the charcoal canister. The fuel cap itself should be non vented. Air should move in and out of the tank through the charcoal canister. That way, all the fuel vapors get trapped and burned.

Yup, but with the FI tech fuel injection my vent line will now be hooked to the fuel Command center... Oh and the cap I asked about is not vented

The cap on the closed charcoal canister system does have a relief vacum setting for safety reasons in case the canister line would get plugged. It also has a pressure release. I dont remember what the vacum release setting is but if the tank pulls so much vacum in it the non vented cap will open its vacum vent but it has to reach the caps setting. Under normal conditions it vent through the canister setup as stated. Ron

Yup this is why I am looking for a way to vent my fuel system.

I agree with everything everyone posted here except you. The filler cap does not vent the tank normally. It is a pressure vacuum cap like what 383 stated above. It only vents in a emergency and does not help vent the tank. There should be a slight vacuum when you loosen the filler cap, that indicates the system is working properly and keeping the gas smell out of your garage.

You should keep the factory vent system in place, if you don't want to use the charcoal canister then connect the gas tank vent line to the engine crankcase on top of the motor at the valve cover breather.

Your "command center" should be vented back to the tank at the sending unit connected to the normal return fitting. That way you there again to keep the gas fumes out of your garage and the air.

Get a sending unit with a return fitting if you don't have one now for your command center venting.

If you vent through your cuda filler cap then you will be leaking fuel every time you step on the gas, don't be one of those guys.

Do not alter the factory tank venting system, use it it works best.
71 cars vented the tank to the valve cover breather so I am not re inventing anything, both of my cars are vented like the 71 cars were and I never smell gas ever around my cars.

Good luck with your FI install.

Gates Automotive Replacement and Support

Includes passenger cars, light trucks, marine, grounds maintenance, and recreation.

303-744-5651
apateam@gates.com

Ask them, I think it means it has a roll over valve to prevent leakage in an accident and venting is handled by the emissions system not the cap.

Why don't you keep the stock vent setup and run another line for the surge tank return? You can always add another nipple to the sending unit or in the filler neck.

I called Gates (same number) already, they referred me to Stant who makes their caps (800) 822-3121 where I was sent to voicemail. They have not returned my call

We are on the same page supercuda.

If it were me I would use a return line, the return line hemis and 440 6 packs used and vent the control center to the valve cover breather along with the fuel tank. A return line pays many dividends and I highly recommend you use a return. I saw your other post, a return is a option and should be used IMO. I use returns on both of my cars and it has paid off many times in extreme conditions. I have mechanical fuel pumps too. A electric will live longer with a return I am here to say. They only give you an option of no return to make the install look easier and so they can sell more units...IMO.

In either case you need to get a hemi return line for your cuda, we are lucky our cars came from the factory with hemis because it makes getting and installing a return line easy.

That's what I said, My OE cap should allow air in when vacuum builds but the tank was vented to the charcaol canister.
... and I was looking for a vented cap so I could finish the install and tune it, but the description is misleading on some caps. It's not ideal and not how I want do it but I have calls in to both Fi Tech and the business I bought the unit for specific advice on venting and am waiting for replies.

Thanks I'll see if I can fit a return line in and duplicate the 71 venting.

So I need to vent the Command center to the tank, vent the tank to the valve cover and then run a return.... that is allot of lines

All the sending units I see have a 1/4" return. Looks like I will be modifying one


THANKS to all for your input

Lessons learned today

1- That Gates aftermarket fuel cap actually does vent but at 2 PSI (if anyone needed to know)

2- The "vent" line from the Command center can/may return fuel, calling it a vent is not accurate. That was one of the things I needed to ask the sales rep

3- You are not suppossed to run a return with the Command center


Did the Earlier E body have anything in it's vent line to catch/prevent raw fuel from making it to the engine? Anyone have a diagram of exactly how it was done?

Yup knew that about the pressure vacuum caps. They are considered non vented. At 2 psi your tank would be ready to rupture.

Here is the factory service manual. I think first you need to get fa miler with your model car. This is a dodge one, I bet plymouth is the same.




I have a 71 and a 74 FSM. I have some betetr pictures somewhere. See if I can find them.

Thanks. I have the 72 manuals but am seeking a factory reference for how Chrysler actually vented the 71's as mentioned earier. It looks like there's a canister in one illustration .

The 71 Plymouth manual is a bit different. The section is titled Vapor Saver, has no index under that and the illustration is different. However, the text is word for word the same.
Files here will not accept my picture since it is too big. If you really need it, I can lower the resolution and post it or email it straight to you.
Craig

The 71 manual does not show a cannister but a "crankcase air cleaner" with a tube to the vapor seperator, one to the air cleaner and one to the carb. There is another tube in the illustration from the PCV valve but the other end is not shown.
Craig

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