I've got a few symptoms that I think might be related. Whenever I try to put gas in the car during or immediately after a track day, the pump will keep trying to click off well before the tank is full (like, starting at less than a quarter tank) unless I fill it very slowly. Also after track sessions when cruising at constant speed around 3k-4k RPM, the engine will sometimes stutter. Finally, after my last track day I noticed a CEL code, P0453 Evaporative Emission System Pressure Sensor/Switch High.

As I understand it, these symptoms are all likely related. What's interesting is that they all only happen after a hard track session. I'm wondering if the fuel sloshing around in the tank, or possibly something to do with heat, is saturating or otherwise messing with the fuel tank evaporative venting, causing both the stuttering while cruising at mid RPMs, and the difficulties filling up. I'm not sure exactly how the system looks or works though, and also not sure if this is just inevitable when tracking with a stock fuel tank, or if it suggests there's a problem with the evap system.

Anyone here know more about this? Have others experienced the same thing? Thanks!

 

If you are still on stock ecu and all EVAP functions turned on like normal then it sounds like there might be an underlaying issue.
Maybe charcoal canister is saturated and barely manages to keep up on normal driving but just cant handle the heat and constant slushing when on track.

 

Yep, stock ECU and I checked with my tuner that nothing related to evap was changed. So it does sound like a saturated charcoal canister could be a good bet. Thanks.

 

I bet that is it. Our local TNIA events are on a short course which is more turns than straights, and I usually have to fill up after 2 sessions and have never had any issues like this. I have smelled gas faintly afterwards (but no signs of filler neck leaks or anything) which I assume is due to some slosh and some getting into the canister and thus creating a tiny amount of smell from the vent. But the issue you describe, especially after track use, would make me guess canister saturation is likely the issue.

 

Took it in to a shop who went through the service checklist for these codes. There's actually a test you can run with a scan tool where it'll actuate the valves and such and test tank pressure. They verified that it isn't the canister - actually had another S2000 that they were able to swap a known good one in from, and it didn't make a difference. After going through everything easily accessible, it's narrowed to the vent valve on top of the fuel tank, 17725-S2A-A52.

Unfortunately that guy is nationally back-ordered with no in-stock date. And it's apparently 7 hours of labour to change since you have to drop the tank.

So I can wait an unknown time period for a new part, or can see if they can clean the one I have and get it working, potentially wasting $7hours. Don't suppose anyone has one lying around!

 

Any idea on the cause of it going bad? I'd like to avoid this happening in the future, especially if the fix is so labor intensive and on a part that is back ordered...

 

Did you have any symptoms other than the ones listed here? I've had similar things happen once after leaving an autocross and once after a track day. It hasn't happened autocrossing this year and I have yet to do a track day. After the last track day in 90+ degree weather, car was perfect in all sessions. Then leaving the track, it started breaking up pretty badly at low RPM. I think it didn't fill smoothly at the gas station but I didn't particularly note that. It cleared up pretty quickly and I drove it 4+ hours home. Is there any longer term impact that you are afraid of or think could happen if you don't change it? What makes you think that the valve would have this type of impact?

FWIW, my car is an 06+ with 2 seasons of autocross and 3 track days in Solo street trim (sticky tires and a sway bar).

 

The shop I took it to ran a diagnostic test for the evap system. The test failed saying there is too much pressure in the tank, despite that not being the case (happens regardless of actual tank pressure, which they can measure at the filler neck).

After checking for anything obvious, they're following a diagnostic flowchart for P0453, and went through all steps up to checking and replacing that valve/hose. That said, it seems a bit odd to me on reflection. I would think the vent would be the problem if the pressure was actually high, but if it's just reading high when it isn't, that sounds more like a fuel tank pressure sensor. This, maybe? https://www.hondapartsonline.net/oem...re-37940sdaa01

 

If the pressure isn't actually high, what are you thinking is causing the inability to fill and stuttering? I understand the pressure sensor may be your CEL but what about the actual symptoms?

Wish I had more to offer here but I didn't really get anywhere with the thread I started and haven't really pursued it further. It's happened twice to me in 3+ years with no CEL.

 

I think the pressure was actually high after the track. I never actually got a CEL btw, just a pending code.

But when they're diagnosing at the shop, the evap system diagnosis is returning fuel tank over pressure and (my understanding is) it was doing so regardless of the actual pressure in the tank, even if the filler was open. So to me that suggests a sensor issue. But yeah, I don't understand how that would relate to the symptoms I'm seeing. I don't really know exactly how the system is supposed to work though.

Maybe 17725-S2A-A52 has an integrated sensor?