Fuel system vapor separator original purpose (edited)

[Speedrdr]

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.

That would be why there ain’t one on my 77. And all this time I was thinking that a PO had yanked some stuff off the fuel system, being as the cobbled together mess of fuel lines between the tanks and fuel pump.

Randy

 

[ksagis]

This has been interesting thread for sure, so Ford called it an expansion tank, but if later models eliminated the tank and added a rollover valve, that makes me think the “expansion” function wasn’t actually needed and it actually provided more of a roll-over, anti-siphon functionality. Thoughts?

And while noodling on this issue, for the vehicles with the unvented gas caps like these, where did the tanks get air as the fuel was being depleted? Was there another OEM hose/fitting with a one way valve that let air in, or did the system pull air via a reverse flow through charcoal system back into the tank?

 

[Oldtimer]

My 68 has vented gas caps.
The main tank has a vent line that is plumbed from the tank to the filler neck.
The aux tank relied on the filler neck only for venting, very difficult to fill tank.

 

[DirtDonk]

It was my understanding that later “non-vented“ gas caps were in fact more of a “one-way vented” kind of thing.
Allowing air in, but not out.

 

[DirtDonk]

But, even if that’s not the case, a tank equipped with an evaporative emission system (charcoal canister), could certainly allow air back in through its tubing to compensate for fuel used.
I’m not aware of anything in the way of a check valve to keep that from happening.

 

[gnsteam]

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.

Anyone have a picture of this anti-rollover valve. I don’t remember removing anything during my restoration of the frame.

 

[Oldtimer]

In this thread:

Where to get this anti-rollover valve protector bracket?

I am looking if anyone has seen a source for one of these brackets? I think they were used on the 76 & 77 frames to protect the anti-rollover vent valve in the line between the fuel tank and the charcoal canister. Thanks!

classicbroncos.com

 

[Steve83]

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.

Fuel (or any liquid's vapor) can only condense in areas where the temperature is lower than where the liquid is evaporating. And I can't imagine very many situations in which the quarter panel or interior of an early Bronco (as-built by Ford) would be colder than the gas tank.

...so Ford called it an expansion tank...

Part names in the Ford system are VERY often confusing, misleading, or just absolutely wrong. Case in point: when F-series/Broncos got a driver's airbag in '94, the sliding contact that had been used for horn & cruise connections between the column & wheel was replaced by the now-common "clock spring". But for SEVERAL years, Ford's parts system continued to call it "airbag sliding contact" even though that's exactly what it is NOT. So you can't conclude anything useful based on the Ford parts-system name. The PCED name would be more-accurate.

 

[gnsteam]

In this thread:

http://[URL]https://classicbroncos....anti-rollover-valve-protector-bracket.310562/

[/URL]

Thanks for the link. Looking through my frame tear down pictures. My 76 did not have one. Something I will have to add to my build.

 

[DirtDonk]

First time (and only time that I remember) was on a friends’77.
I may have seen maybe one more, but if so I probably wouldn’t have noted the year model anyway.

 

[DirtDonk]

I have seen 76 models with the old steel low mount charcoal canisters, but I have also seen many (including one owned by wild horses) with the later high mount plastic canister.
It’s still connected on “Gramps” so I’ll have to check the frame rail next time I see it.
And get a build date off of it too.

 

[DirtDonk]

Maybe this is a good opportunity for some up-n-coming videographer to set up a view on a fully functioning original '70-'76 EB with the tank in the cab. We can then watch it as the tanks are filled up, during driving, and maybe even while four-wheeling! Then with a full tank, while the ambient temperature increases during the day.
I'd love to see just what is going on inside it during normal use.

When mine developed a leak (top seam split) it would only smell like gas in the cabin right after a fill-up.

Paul

 

[AZ73]

This is mine from a 1973. The white sticker is on the back. Part number reads: D3TA-9A091-BA. Try finding a replacement rubber gromet it slides into. I had to restore the old one by using a warm water/amonia bath then soaking it in Gummi Pflege Stift. Not perfect, but much better than it was.

 

[Steve83]

Well, the engineering number molded into it says it was re-engineered in '73, and that there were at least 2 versions before it.

 

[CopperBronco]

Same convo here and how I solved on my Bronco… https://classicbroncos.com/forums/threads/charcoal-canister-evap-install-solve-gas-smell.313910/