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Trying to sort out an issue on our 05 Odyssey EX. The van is currently giving a large leak code, and I am struggling to find where it is. The code seems to only trigger when the van is driving based upon freeze frame data from my code reader.
A while back, every once in a while when we filled the tank in the summer, we would get a strong fuel smell by the charcoal canister (nothing in the engine compartment) – everything looked fine, and the issue was very intermittent, so we lived with it. I replaced the fuel filter (there is actually a recall for the top of the fuel filter cracking – ours was, but there was no gas odor from the top of it…) – replaced the gasket and filter – everything remained more or less the same. More recently, the car started throwing the minor leak code – the gas cap seemed fine (no damage to the gasket, and the fuel smell was not from the gas cap area) – started digging a little. The purge solenoid is working properly (opens/closes as it should with power, and doesn’t leak) but the vent valve (at the canister) seemed to be pulling a lot of current, and wasn’t closing as quickly as it should. Replaced it, along with the gas cap (both new Honda parts) – no real change – still throwing the code. Pulled the various lines and checked the o-rings and sealing surfaces – no damage, everything seems secure.
Decided the check the lines around the evap vent shut float (large assembly that goes up from the tank adjacent to the fuel filler neck) – all of the connections seem sound. Pulled the two lines that go to the top of the tank and one of them had a bunch of fuel on it (mostly in the line as it went up to the float valve, rather than the line as it goes up to the top of the tank) – I drained it as best I could, then reassembled everything. To diagnose the valve, you basically pull a vacuum on one line and measure it on the other (of the two I pulled) – I don’t have two vacuum pumps, but my reasoning is that if one of the lines is plugged (albeit with a slug of liquid fuel) when you pull vacuum on one, there will be a lag before you see vacuum on the other – the service manual states the change should be immediate, and if it’s not, then to replace the vent shut float.
I am not sure if this is the culprit or not. It’s not a terribly expensive part ($100 or so) but it’s no fun throwing parts at it without knowing what’s up. I don’t have a smoke machine, so I am not sure how else to diagnose. All of the lines I have had access to appear to be sealed properly – o-rings are undamaged, and the sealing surface is clean/undamaged… only o-ring remaining to check is the pressure sensor on the top of the canister, but I can’t believe a small leak there would cause a strong fuel smell…
Any thoughts?
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These leaks can be hard to find unless something is split or obviously broken.
A smoke machine is the best way which I know you don’t have.Hi,
can’t vouch for yours, but on my van it ended up being the filler pipe, it had a couple of holes rusted through it, might be worth a look.Chevyman
When I pulled things apart the other day, I was thinking maybe the fuel filler neck, but it’s solid with no cracks/holes that I could see (it’s plastic, just like the tank, and the joint at the fuel tank and at the very top of the filler (where the flange that the filler cap screws onto is) looked solid/sound) I really couldn’t find anything that looked out of place. The van has quite a few miles on it (>215k), but given our location, there is virtually no rust/corrosion (makes working on cars really nice down here as compared to the northeast where I grew up!)
Now, the fuel smell we had before I drained the vent float assembly seems to be gone… I am cautiously optimistic that the liquid fuel in the float line was the source – next time my wife fills up I will see if it smells strongly of gas, and if so, see if the line is has fuel in it and see if draining it helps. I am guessing the float valve is letting fuel in where it shouldn’t be, then doesn’t function properly… we shall see, I guess.
Ok – so I think I have two issues, and have hopefully addressed one. The first issue is the strong fuel smell after filling up, and the second is the leak which is triggering a P0455.
For the leak triggering the code, I think I addressed it. The vent shut valve wasn’t working properly, so I replaced that (still leaked), the gas cap was original (van has 220k miles on it) so I replaced that (all OEM parts) – still leaked – replaced the vent float control valve along with the o-ring for the pressure sensor on the canister, and I think it’s not leaking any more (or at least it hasn’t thrown the code yet) – the charcoal canister holds pressure without leaking, so I think that’s sound, and I checked all of the hoses and fittings, and they seem snug/clean and sound.
Second issue (the fuel smell after filling up) seems to persist. It did that long before we had the small then large leak codes, so they could be unrelated… there is no fuel smell in the engine bay, nothing around the fuel cap, but under the car by the charcoal canister (where the vent is) it seems to be pretty strong. I don’t think there is an actual fuel leak, since it just happens when the car is freshly filled, and there are no signs of liquid dripping/running down the side of the tank – plus, a source of liquid gas tends to smell stronger than this, in my experience.
So now my thoughts go to the charcoal canister – if the float valve had failed (there was liquid gas in some of the lines when I was checking it), would getting liquid gas in the canister poison it, or otherwise substantially reduce it’s efficiency? It seems plausible, but that doesn’t mean it can happen… air blows freely through the canister and the filter that’s after it, so it’s not plugged per se, but if the canister contains activated carbon (which is usually nanoporous particles) the material can be poisoned based on my work in unrelated areas…
The wife insists that she never overfills, and always stops at the first click when the pump turns off, so we’ll go with the tank has not been overfilled recently…
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