Fuel system vapor separator original purpose (edited)

[ksagis]

Anybody have a theory of the original purpose of the condensation tank behind the driver was? My theory is that since the factory charcoal canister was frame mounted below the tank, the needed to have a way to prevent liquid gas getting to the charcoal canister, so they created the condensation tank. It *might* have some rollover benefit, but hard to tell since I never pulled one apart.

Which leads to my next question, I'm very likely going to do the Mustang charcoal canister conversion mounted in the engine compartment (higher than fuel tank), and if I do that, there's no reason to keep the condensation tank in the circuit anymore?

Any thoughts appreciated.

 

[Steve83]

IDK where you got the name "condensation tank". Yes, it's a liquid separator, and it should stay regardless of charcoal canister position. It could only be replaced by adding a later rollover/vent valve to EACH tank.

 

[ksagis]

Thanks for clarifying the correct name, title of thread updated.

Do folks think the purpose of it is to act like a method of stopping fuel flow for a rolled over vehicle or is the purpose something else? To my knowledge of reading on the forum, EBs didn't have rollover valves on them, did they?

 

[DirtDonk]

Right or wrong, it’s been called a condensing tank for 40 years and then some.
Yes, it’s probably a separator. But it allows fuel vapors to condense into liquid and drain back into the main tank.
So it’s a separator, and a condensator.
A floor wax, and a dessert topping!

Either way, it allows liquid fuel to flow back to the main tank. It does work as a fairly effective rollover catch tank as well.
Up to a point…

And no, you no longer need it. The whole point of the change Ford made to the newer style charcoal canister under the hood was to eliminate any fuel possibility in the cabin.
Which I’m pretty certain it was a federal mandate of the time because that’s when all the gas tanks left the cabs of pick up trucks.
And the last of the exposed gas caps disappeared about that time as well.

 

[ksagis]

@DirtDonk , thanks for information.

In one of your previous posts on this topic, you mentioned that the later model EBs deleted the vapor separator and moved the charcoal canister to the firewall. When they did that, do you happen to know if they added any loops to the line to raise it higher than the fuel tank in the back quarter panel area (for a high point to keep fuel out of the line in normal operations)?

 

[DirtDonk]

No loops or different heights. The 76 and 77 broncos had an anti-rollover valve mounted to the passenger side frame instead.
Standard tubing everywhere else between the tanks and the canister.

 

[Broncobowsher]

'77 was the year the exposed fuel caps were not allowed. This was an anti-sideswipe fix. Recessed fuel caps so a side swipe won't shear off the cap. There were still exposed fuel caps in the 21st century (Aztek) but they are in a recessed pocket.

I always felt the condensation tank was also an anti-siphon device as well. With a low mount charcoal canister and a direct line to the fuel tank, if parked down hill it could siphon a bit off a full tank. A high mount charcoal canister eliminates that (in normal driving/parking)

 

[jamesroney]

'77 was the year the exposed fuel caps were not allowed. This was an anti-sideswipe fix. Recessed fuel caps so a side swipe won't shear off the cap. There were still exposed fuel caps in the 21st century (Aztek) but they are in a recessed pocket.

I always felt the condensation tank was also an anti-siphon device as well. With a low mount charcoal canister and a direct line to the fuel tank, if parked down hill it could siphon a bit off a full tank. A high mount charcoal canister eliminates that (in normal driving/parking)

Not sure about any mandate or statute, but I agree with your anti-sideswipe logic here.

The (Willys / Kaiser / AMC / Chrysler / Daimler / Fiat / Stellantis) Jeep Utilized an exposed fuel cap from 1942-2018.

100% agree with your siphon break conclusion.

 

[jamesroney]

IDK where you got the name "condensation tank". Yes, it's a liquid separator, and it should stay regardless of charcoal canister position. It could only be replaced by adding a later rollover/vent valve to EACH tank.

I also don't understand the nomenclature here. I understand the liquid separation function, and the vacuum break, and the roll-over protection. But I have always been baffled by the name of the device, and the reason for it's volume or capacity.

I wish that someone with access to the MPC or a Factory Service Manual could identify it, and provide the actual name (and part number) of the component. (hint, hint...)

 

[DirtDonk]

I’ve been promoting the name “condensing tank” for years on the forums.
Can’t remember if I read it in one of the books, or heard it on the Internet. But it’s stuck in my brain and that’s what I’ve been using.

My go to books were always the Haynes and Chiltons, so it might’ve been in there.
Easy to check when I get a chance.

 

[DirtDonk]

The (Willys / Kaiser / AMC / Chrysler / Daimler / Fiat / Stellantis) Jeep Utilized an exposed fuel cap from 1942-2018.

Were there any that actually stuck proud of the body? At least on the universals?
All the Universal/CJ series have been in a recess for many years. Possibly even from the very beginning. Correct?
Might even have been a military design requirement?

Not sure about the pickups, but many of those were of a “stepside“ type bed design where the exposed filler neck and cap were still proud of the sheet-metal, but recessed behind a wide fender/wheel well.
At least I think that’s what I remember about them.
Those features were likely enough to overcome any changes in regulations I would think.

 

[jamesroney]

Were there any that actually stuck proud of the body? At least on the universals?
All the Universal/CJ series have been in a recess for many years. Possibly even from the very beginning. Correct?
Might even have been a military design requirement?

Not sure about the pickups, but many of those were of a “stepside“ type bed design where the exposed filler neck and cap were still proud of the sheet-metal, but recessed behind a wide fender/wheel well.
At least I think that’s what I remember about them.
Those features were likely enough to overcome any changes in regulations I would think.

Well, it kinda depends on what you call "the body." On the 1950-52 M38, (which is not CJ) the gas tank cap most certainly extends past the body side...but does not extend past the "fuel tank guard" which looks an awful lot like a grab handle! Yes, the Willy's pickup fill neck extended way past the stepside bed. Easily and often used as a step when not equipped with the optional Barden bumper.

But on the CJ-2a with the under-seat tank...I'm going to say that the cap extends past the body side, but not past the soft top bow storage pockets. So it's a maybe. CJ-5's are tucked in, and of course the fuel pocket moved to the rear in 1972. But it came back in 1997.

But the Chevy C10 did not get fuel doors until 1979. I hate to use the worlds most stupid gas tank fill design as an example for anything...but it's the only one I can think of.

 

[Ovalis]

While we're talking about this "tank". In Ford's schematics for the fuel system, they show a valve with hoses mounted to the top (and outside) of the tank. I've never seen tank with a valve associated with it. Has anybody else?

 

[Speedrdr]

I delved into the 7 volume, >2,000 pages 1977 Ford Truck Service Manual that covers all tracks, including the Bronco and up to the F-450, and the following pics are ALL it said about the system of vapor control and what they call it. Pretty sparse info for something that important, in my opinion.

Randy

 

[Speedrdr]

Should have circled the paragraph to make it easier to find. It’s the bottom right hand paragraph named “carbon canister”.

Randy

 

[Oldtimer]

I wish that someone with access to the MPC or a Factory Service Manual could identify it, and provide the actual name (and part number) of the component. (hint, hint...)

Challenge accepted, I don't feel like laying on ground to work on my Bronco

TANK ASSY. (FUEL TANK VENT EXPANSION)

 

[jamesroney]

I delved into the 7 volume, >2,000 pages 1977 Ford Truck Service Manual that covers all tracks, including the Bronco and up to the F-450, and the following pics are ALL it said about the system of vapor control and what they call it. Pretty sparse info for something that important, in my opinion.

Randy

Well, yeah. The D3TZ-9A091-A, Tank Assembly, Fuel Tank Vent Expansion was gone by 1977. So it wouldn't be in a 77 Shop Manual. That makes sense.

 

[jamesroney]

Challenge accepted, I don't feel like laying on ground to work on my Bronco

TANK ASSY. (FUEL TANK VENT EXPANSION)

View attachment 904267
View attachment 904266

Good try, and I'm going to give you partial credit. But there will have to be one for the 1970 year model...and it should have a D0TZ prefix. I am optimistic that it will have the same nomenclature.

 

[Oldtimer]

All I have is the 73-79 MPC.
May have to pick up the 65-72 version when I get my next social security check.

 

[jamesroney]

Good try, and I'm going to give you partial credit. But there will have to be one for the 1970 year model...and it should have a D0TZ prefix. I am optimistic that it will have the same nomenclature.

And the 1975 MPC confirms that the 9A091 is in fact a Tank Assembly, Fuel Tank Vent Expansion. Thanks @Oldtimer . Used in the Bronco as a D0TZ-9A091-A, and -B. Also used in the F series Truck as the -D, and -E. And used in passenger cars as shown.