How I fixed the fuel filler problem

While filling the tank all of the displaced air must pass through the charcoal canister and then through the air filter located on the left of MordacP's first photo.

My FJ has never had difficulty filling (note it has no lift) so I've wondered why some have had. Perhaps their air filter has become clogged with dirt preventing free passage of the air.
When I installed an aux tank this past summer I inspected my air filter and it was clean.


Some additional thoughts / observations:
The 1" fill pipe is much larger than the amount of fuel that goes in, so that is unlikely to be it.
The small diameter pipe is for shutting the filler nozzle off (a small jet of fuel shoots up it when the tank is filled, to "tickle" the end of the nozzle and trip its shut off before the 1" column of fuel can come up the neck and splash out).
The third pipe (middle sized) that runs up alongside the main filler pipe is the snorkel for the air filter. It has a "head" wrapped around the main pipe at the top (just a baffle to help prevent dirt getting in).

Anyone having difficulty filling their FJ try this experiment:
- remove and inspect/clean the air filter, and then blow air up that snorkel, toward the filler, to make sure there's no dirt clog.



Norm

Norm 356 wrote: "While filling the tank all of the displaced air must pass through the charcoal canister and then through the air filter located on the left of MordacP's first photo."

Are you certain this is the vent path for air and fuel vapor that are displaced from the fuel tank during a fuel fill? Evidence?

This doesn't correlate with my observations while fueling an FJ or any other vehicle.

Without an actual vapor-proof seal between the fuel fill nozzle and the vehicle's fill port, fuel vapor is free to flow out of the tank through the fill port and out through the clearance between the filler nozzle and the fill port.

That's the reason for the 'foreskin' on the fill nozzle (in areas that require it) that captures the escaping vapor ... without the vapor capture system on the fuel fill pump, the vapor just escapes.

I don't believe the charcoal canister has the flowrate capacity to handle the several cubic feet of saturated fuel vapor that is displaced during a fuel fill - that vapor needs to be captured by the fuel filler pump system.

The charcoal canister under the cargo bay is there to capture any small amount of fuel vapor that may be forced out of the tank because of temperature changes and/or atmospheric pressure changes.

(With no body lift, I have never encountered any problem with premature fuel nozzle shutoff after only 1-2 gallons of fuel are pumped on my 2014. I can usually get another gallon in after the first nozzle shutoff if I rock the vehicle slightly and wait a few seconds before resuming filling.)

The charcoal bed in the engine air intake filter housing is there to capture any small amount of fuel vapor that may escape from the intake manifold (or from cylinders with open intake valves) after engine shutdown.

I did find this from Toyota, which doesn't fully answer the question. It looks like there is a primary fuel tank vent line that just terminates at the fuel fill port, but it also has a vent line back through the canister. I could not find a clear description of the function of the 'Refueling valve'.


Also, here's a diagram of the ORVR (Onboard Refilling Vapor Recovery) system used on some Toyota models - with this system, fuel vapor is clearly directed back through the canister during fueling. Applicable to FJ?