Gas smell - charcoal filter

[dhendriksen]

Just got my Bronco back after a full restoration - smells like gasoline. I have the dual tanks from the factory. My gas caps are the paintable ones from Tom’s.

I know the builder ditched the evap system. The one for the front tank (like tank behind the drivers seat) was there but is now gone. The softball size one that I believe was for the back tank…I still have it, but it’s never been installed during my ownership. It smelled bad before the restoration as well.

What would you professionals recommend I do to get rid of the gas smell that can handle both my tanks? I’ll likely do this myself (but could as it as a punch list item for the builder) so as much description on instruction as you can provide would be amazing.

 

[DirtDonk]

If it had the recovery tank behind the driver’s seat, that was for both tanks.
Two lines come from the main tank into the canister, and one line from the auxiliary side tank.
From there an additional line goes up front to the frame mounted charcoal canister, where any excess fumage gets sucked into the engine through the air filter.

Removing that has worked for some, but it’s almost never a good idea. For every Bronco owner that doesn’t smell gas after removing the system, 20 others do.

First things first. Since they are still the stock tanks, find out what the restoration shop (If you can call them that when they don’t put things back to stock) did with the vents on the tanks.
Did they cap them off, plug them up, or leave them open. Or did they leave the hoses intact.
If hoses, follow them and find out where they go.

Find that out and let us know.

 

[dhendriksen]

Alright, so I got under the Bronco and checked this out. The little tank behind the driver seat is most definitely not there. I’m sure he still has it, and I can add to my punchlist that he needs to put it back. I also have the original charcoal filter and can have him bake, paint and reinstall that. I just need new hoses.

As it is now, the vents are capped. The aux tank isn’t currently being used because there’s a leak at the sending unit (a punch list item for him, so that tank is drained) but that vent is capped. The main tank just as a hose that runs between the two vents.

Is my best course of action to put that little tank back behind the drivers seat, and reinstall the charcoal filter, all as it were from the factory? Or am I better off doing something else, as I heard those little tanks in the cab often times start to leak and become problematic. I have the entire interior all put together and I’m not excited about the prospect of undoing the entire thing to put that tank back in.

 

[DirtDonk]

Yeah, leave the old in-cab tank out.
I would still make them give it back to you because it’s yours and part of your vehicle. You can decide to toss it out later, or sell it to someone who wants to keep their original.

Don’t bother to restore your existing charcoal canister either. Simplify the whole thing, and get the gas out of the cabin, by going to the 76/77 model.
That is a plastic charcoal canister similar to most 80s passenger car, models, mounted up high on the passenger side firewall.
You can leave one of the vents on the main tank capped off, or T them together and run the line directly to the new charcoal canister.
Rubber line is temporally acceptable I suppose, but metal line would be better in the long run.

So this kills two birds with one stone. So to speak…
Venting the tank into a new charcoal canister, and getting all the gas out of the cabin.
Still won’t guarantee a Bronco no fumes of course, since the tank itself can leak if not careful. But it goes a long way.

 

[DirtDonk]

There are discussions about this modification here on the forums. Lots of people have done it over the years.

 

[Jedeka]

There may be better answers, but I have been saving info for my build. I believe people have been mounting a Foxbody Mustang charcoal canister on the passenger firewall and running hoses to the gas tank(s).

 

[DirtDonk]

For the record, the picture of the blue bronco above is my ‘68 before it was fully plumbed.
When a system like this is correct, either the medium size port, or one of the large ports will be connected by hose to the air filter.
In front of the MAF.

 

[Torkman66]

This might help if your lookin for a DIY option:
https://classicbroncos.com/forums/threads/diy-charcoal-canister.322134/#post-3533735

 

[dhendriksen]

There may be better answers, but I have been saving info for my build. I believe people have been mounting a Foxbody Mustang charcoal canister on the passenger firewall and running hoses to the gas tank(s).

Yeah, I think this is exactly what I’m going to do.

 

[dhendriksen]

For the record, the picture of the blue bronco above is my ‘68 before it was fully plumbed.
When a system like this is correct, either the medium size port, or one of the large ports will be connected by hose to the air filter.
In front of the MAF.

What is the MAF? I was just going to plumb it in to the hole on the bottom of the air cleaner.

 

[904Bronco]

MAF - Mass Air flow sensor

What Paul is saying is basically the same thing that you are planning, The front of the MAF is where the air filter would be attached.

 

[DirtDonk]

This way, even the small amount of extra air and fuel is metered going into the engine.
So even though it’s a mixture, where normally the engine would expect air only, the volume is counted by the MAF. Letting the O2 sensors do their thing more efficiently.
At least I believe that’s the process going on.

On a carbureted engine, or a speed density, or a throttle body injection engine, it simply needs to go to the air cleaner on top.
If it’s an open element air cleaner, then it should go to the port or hole or fitting inside the filter closer to the Venturi.
If it’s a closed element, stock type filter, it can simply be attached to the housing anywhere away from the snorkel.

The images that Jedeka posted just happened to be of fuel injection set ups.
What is yours?

 

[dhendriksen]

This way, even the small amount of extra air and fuel is metered going into the engine.
So even though it’s a mixture, where normally the engine would expect air only, the volume is counted by the MAF. Letting the O2 sensors do their thing more efficiently.
At least I believe that’s the process going on.

On a carbureted engine, or a speed density, or a throttle body injection engine, it simply needs to go to the air cleaner on top.
If it’s an open element air cleaner, then it should go to the port or hole or fitting inside the filter closer to the Venturi.
If it’s a closed element, stock type filter, it can simply be attached to the housing anywhere away from the snorkel.

The images that Jedeka posted just happened to be of fuel injection set ups.
What is yours?

Mine has the factory carb that they put on it in September of 1970.

 

[DirtDonk]

First few months of the charcoal canister system. Is yours registered as a 70, or a 71?
That was right near the changeover, so wouldn’t be surprised at all if it was a very early 71.
In your case, it would be simple if you still have the factory air cleaner. Just run a readily available emissions hose from one of the large capped off ports directly over to the plastic fitting on the air cleaner housing.
Utilize the small port on the canister for the vent from the tank, and leave the medium pork capped off.
When using dual tanks, simply Tee their vent lines into each other back near the tanks.

 

[dhendriksen]

First few months of the charcoal canister system. Is yours registered as a 70, or a 71?
That was right near the changeover, so wouldn’t be surprised at all if it was a very early 71.
In your case, it would be simple if you still have the factory air cleaner. Just run a readily available emissions hose from one of the large capped off ports directly over to the plastic fitting on the air cleaner housing.
Utilize the small port on the canister for the vent from the tank, and leave the medium pork capped off.
When using dual tanks, simply Tee their vent lines into each other back near the tanks.

Mine is indeed a 1971. I was planning to either run the two tanks to a T and then run up to the charcoal filter, or run the aux tank vent to the main tank, then the second main tank vent to the charcoal canister.

I don't have the stock air canister (I do, just not installed)...just a 14" round one sitting on top of the carb.