Does anyone know what these canisters are for?

[nickeboy]

There are two canisters under the passenger side of my bronco. Both seem to have a vent tube or fuel line tubing. Neither of them go anywhere they just vent up to the engine compartment.

 

[Broncobowsher]

Round one is the original charcoal canister, evaporative emissions. Doesn't hurt performance one little bit, reduces the garage stinking of gas
The square one is a retrofitted modern charcoal canister. modernization in suspended progress.

 

[nickeboy]

Never knew they had these. I dont remember this on my 66

 

[spap]

My 77 has the round one on the frame but a bracket on the pass side engine compartment for the second style you have under neath.
the black square one is nor factory at the location I have a junction for the tube from the main tank meets the tube for the aux tank

 

[DirtDonk]

Never knew they had these. I dont remember this on my 66

A '66 through early '70 would not have had one.
They used the round frame mounted canister from mid-'70 through mid-'76 or so. But if spap's '77 was original, then they mixed them up a bit now and then. Just like we've found on other areas of Broncos!
Sometime in '76, at least some Broncos got the later style plastic canister, mounted high up on the passenger side firewall in the engine compartment. All '77's "should" have had one, but maybe they didn't.
Kind of hard to imagine they messed with the new design, because it was part of the regulations that kept any fuel out of the passenger compartment. And the low-mounted canister needed the recovery/condensing tank mounted inside the cabin.

I think we talked about this a few years ago, didn't we spap?
Are you the original owner? It's always possible that someone didn't like the O.E. one and retrofitted the early style. Or the original one got damaged (or more likely removed by a PO) and was replaced with the only type that they knew.
Whatever the reason, I'd be curious about any other differences. And if it was a FED spec truck, or a CA spec truck.
On full-size trucks, certain GVWR trucks did not even have a canister right up to the '77 model year. After that though, I'm pretty sure by '78 even the heavy trucks had charcoal canisters.

And nickeboy, I'm not certain, but I'd say that your plastic one mounted under the truck is not functional. It's not mounted vertically, and they are ALL mounted vertically. It's not mounted high up and vertical, and all of those on Broncos at least were mounted higher up to keep liquid gasoline out of them. Gas is the death (at least temporarily) of the charcoal media inside.
I would remove the one underneath, and either re-plumb the old one, or better still, re-mount the plastic one up on the passenger side firewall and plumb that one to the engine and tanks instead.
That way you can remove the recovery tank in the cabin. Assuming it's still there?
Is there a panel on the driver's side, right behind the front seat, screwed to the body? If you look inside the left rear wheel well, can you spot the oval hole in the body panel to the front of the wheel well and see if there is still a rubber grommet with 3, or 4 tubes/hoses poking through?

By the way... Stock gas tank(s) and fuel system? Or modified?
What year is your Bronco?
Your canister looks like the smaller (lower profile) passenger car version. Our trucks used a fairly deep one with that large rock shield attached. I replaced my larger one with a lower profile one from a junkyard Pinto because I liked the lower profile. I wheeled a fair amount and liked the added clearance. I'll take a measurement and see if it's the same as yours, or shallower. Or maybe someone has another original they can compare to. Your canister just looks smaller to me than I remember.

Paul

 

[spap]

Man Paul you have a great memory, haaa. yea 10/76 build built in San Jose originally ca truck,
has the frame canister and the bracket for the plastic One in the engine compartment
it looks petty original

 

[DirtDonk]

Maybe it’s like one of those Viperwolf “P’s and Q’s“ Ford things.
The running change had started, but they still continued to use the old stuff occasionally. I have seen 76 models with the new plastic style, and ‘77’s (other than yours and maybe any others we’ve talked about here) I’ve never physically seen a 77 with the early style.
But as an October 76, yours certainly qualifies as a legit 77, a couple of months into the production run. But we’ve seen a lot of other discrepancies with 76 models, so maybe this was one of them.

 

[nickeboy]

A '66 through early '70 would not have had one.
They used the round frame mounted canister from mid-'70 through mid-'76 or so. But if spap's '77 was original, then they mixed them up a bit now and then. Just like we've found on other areas of Broncos!
Sometime in '76, at least some Broncos got the later style plastic canister, mounted high up on the passenger side firewall in the engine compartment. All '77's "should" have had one, but maybe they didn't.
Kind of hard to imagine they messed with the new design, because it was part of the regulations that kept any fuel out of the passenger compartment. And the low-mounted canister needed the recovery/condensing tank mounted inside the cabin.

I think we talked about this a few years ago, didn't we spap?
Are you the original owner? It's always possible that someone didn't like the O.E. one and retrofitted the early style. Or the original one got damaged (or more likely removed by a PO) and was replaced with the only type that they knew.
Whatever the reason, I'd be curious about any other differences. And if it was a FED spec truck, or a CA spec truck.
On full-size trucks, certain GVWR trucks did not even have a canister right up to the '77 model year. After that though, I'm pretty sure by '78 even the heavy trucks had charcoal canisters.

And nickeboy, I'm not certain, but I'd say that your plastic one mounted under the truck is not functional. It's not mounted vertically, and they are ALL mounted vertically. It's not mounted high up and vertical, and all of those on Broncos at least were mounted higher up to keep liquid gasoline out of them. Gas is the death (at least temporarily) of the charcoal media inside.
I would remove the one underneath, and either re-plumb the old one, or better still, re-mount the plastic one up on the passenger side firewall and plumb that one to the engine and tanks instead.
That way you can remove the recovery tank in the cabin. Assuming it's still there?
Is there a panel on the driver's side, right behind the front seat, screwed to the body? If you look inside the left rear wheel well, can you spot the oval hole in the body panel to the front of the wheel well and see if there is still a rubber grommet with 3, or 4 tubes/hoses poking through?

By the way... Stock gas tank(s) and fuel system? Or modified?
What year is your Bronco?
Your canister looks like the smaller (lower profile) passenger car version. Our trucks used a fairly deep one with that large rock shield attached. I replaced my larger one with a lower profile one from a junkyard Pinto because I liked the lower profile. I wheeled a fair amount and liked the added clearance. I'll take a measurement and see if it's the same as yours, or shallower. Or maybe someone has another original they can compare to. Your canister just looks smaller to me than I remember.

Paul

Hey Paul, First off, thanks for always jumping on here and helping out. You have helped me multiple times.

This is a 1971 Bronco. New to me. I'm going through the suspension system currently. The bronco is mostly stock with a few PO upgrades. The C bushings and suspension has never been changed. Death wobble scary. The original 302 has Sniper EFI system installed. It starts much easier than my 66 carbed Bronco.
This 71 has a 23 gallon aftermarket tank and it looks like the auxiliary has been replaced. Look at my previous post about the long gas filler neck. Not sure what to do with it.