@HSTexan He's got a point. If you choose the crusher, I'll haul it off for you.It's probably worth having a competent mech test all the EVAPs. Or just take the LC to the crusher...it's a write off
Misfires on 3 cylinders—likely evap issues, flooded charcoal canister led to misfires (2021, 75K miles)
- Thread starter HSTexan
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How often have you forgot to switch it off? I’ve been guilty of this as well but only a couple times and only for a few minutes over 15 minutes. I now set an alarm on my phone to remind me.
I hope this is the fix for your Cruiser!
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- #123
I could not get a straight answer about this, and even asked if they had a photo of all the plugs together last week when we were going doing that path, but from the sound of it from what they told me, the plugs in the 6 and 8 were the quite a bit noticeably worse (what I posted pics of) and the others were just pretty bad.
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- #124
I've actually only forgotten to do it once; it was probably forgotten for about 10 minutes. I usually set phone alarms as well, but I happened to be streaming music that day and the alarm just muted the audio and it slipped my mind why. Big brain fart on my part. I usually only transfer when I get down to 1/4 of a tank and I only transfer half the aux tank (15-20 min timer), but that day I had definitely pushed it. I've also boiled gas 3 times, twice when the tank was full enough to leak out of the gas cap some.
I transfer at 1/4 as well and do so until the gauge jumps up, that’s anywhere from 12-15 minutes. It seems like it’s an inevitability that the canister will need replacing with the LRA. We don’t daily ours and it sits in a garage the vast majority of its life so I’m hoping there’s not a lot of EVAP stuff going on since the temps in the garage are stable. I park it full so we’re ready to go on our trips when it’s called upon. So far so good but your experience has been very educational, if it is actually the canister.
Why are yall kicking the man when he is down?
P.S. I will come for moral support during the crushing..
One thing to keep in mind.. due to the return-based fuel pressure control system the fuel in the primary tank will get much warmer than that in the aux..
So while there is an increased fuel volume, the portion that is emitting a lot of vapor when the conditions are correct isn’t much greater.
Though yes external factors can flood it.
I’d wonder about the evap purge VSV if liquid was going through it.
Also.. any theory why only those two plus would see the purged fuel? The nipple for vapor return is right in the middle of the manifold inlet behind the TB. I don’t have any idea how the internal plumbing of the manifold is set up but it seems strange that the fuel wouldn’t be better mixed by the time it makes it into the engine.
So while there is an increased fuel volume, the portion that is emitting a lot of vapor when the conditions are correct isn’t much greater.
Though yes external factors can flood it.
I’d wonder about the evap purge VSV if liquid was going through it.
Also.. any theory why only those two plus would see the purged fuel? The nipple for vapor return is right in the middle of the manifold inlet behind the TB. I don’t have any idea how the internal plumbing of the manifold is set up but it seems strange that the fuel wouldn’t be better mixed by the time it makes it into the engine.
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- #128
No idea--and it's a valid concern and one that still makes me feel slightly uneasy as well. I think it's less that they're the only two and more they ended up being the worst of all the bad. From the information I've been given, none of the plugs looked good or at least normal, those two and cylinder 2 just happened to show problems first. But you're right, I don't like that the specific codes were all on the same bank.
Ok that makes more sense.
It is maybe more plausible that one side of the manifold got more fuel than the other depending on the running conditions when the fuel was ending up in the manifold but it still seems like a stretch.
It’s always easy in hindsight, but when I suspect a charcoal canister has fuel or if a purge valve might be sticking open, I’ll just clamp off the line and continue my diagnosis. Usually that’s enough to point my efforts in one direction or another.
If we could find a way to set-up the full functionality of the LRA switch with the Toyota fuel gauge sender, it could be programed to turn off when the main tank is full:
See page 5 and 6. Option 2 seems attractive, described as "Automatic Shut Off Selected".
If I recall, Toyota's fuel gauge operates on non-standard resistance measurements. Perhaps there's an alternative way to trigger the main fuel tank sender. Calling all electrical guru's!
Maybe something like this could work: MeterMatch Fuel Gauge Interface Module - https://www.tanksinc.com/index.cfm/page/ptype=product/product_id=748/category_id=-1/mode=prod/prd748.htm
See page 5 and 6. Option 2 seems attractive, described as "Automatic Shut Off Selected".
If I recall, Toyota's fuel gauge operates on non-standard resistance measurements. Perhaps there's an alternative way to trigger the main fuel tank sender. Calling all electrical guru's!
Maybe something like this could work: MeterMatch Fuel Gauge Interface Module - https://www.tanksinc.com/index.cfm/page/ptype=product/product_id=748/category_id=-1/mode=prod/prd748.htm
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Glad things are at least moving along and that there was definitely a problem with EVAP system with plausible explanation for misfires.
I think there's still a root issue that's not accounted for. The EVAP being flooded might only be a symptom, and may appear again if the root cause is not addressed.
Might want to take a closer look at the fuel boiling issues. What are your mods for skids? Do you have any fuel system boiling mitigations or insulation applied?
I believe part of the reason this is cropping up for you this year might be related to the recent EPA decision/waiver as a result of the Iran situation to allow cheaper winter blends to persist through summer. Winter blends have a higher Reid Vapor Pressure (RVP) by design, to facilitate ignition in the cold of winter. That same formula in summer creates more volatility and more load on EVAP systems. Combine that with a rig that traps more heat with skids, but also has increased fuel thermal loads due to the LRA placement in proximity to the muffler, can lead to fuel boiling issues that overwhelm the EVAP and engine. It might be liquid fuel going into the purge valve for which the manifold will not flow evenly as it was designed gasses.
Addressing points others have brought up
- No, fuel fill level generally does not affect RVP. But it can affect how much heat the fuel system can sink from heat sources before increasing in temp significantly and boiling. So more fuel may allow the fuel to stay cooler longer before its heat soaked.
- IMO, the return fuel system being hot is a red herring. That's always been accounted for in the system design. It's mods that add to the heat load of the fuel system that overall creates issues.
That said, there's documented effective mods around the fuel system, tank, LRA, and even the return system that works. I no longer have fuel boiling issues (at extreme elevation).
- Thread starter
- #133
I've read through that thread a number of times--it's likely time to bite the bullet on taking some preventative steps myself. The only times I boiled gas were when I had freshly topped off and had full LRA and near full main tank, in August in Texas when it was 100° outside and we had been wheeling all morning. The other was at elevation in Colorado, on Kelly Flats during LCDC when we had been stopped for awhile recovering another vehicle, then continuing to push on before stopping for a break (where I heard it). I had just filled up the previous night--though at that time I did not yet have the LRA when that one occurred now that I think about it.Glad things are at least moving along and that there was definitely a problem with EVAP system with plausible explanation for misfires.
I think there's still a root issue that's not accounted for. The EVAP being flooded might only be a symptom, and may appear again if the root cause is not addressed.
Might want to take a closer look at the fuel boiling issues. What are your mods for skids? Do you have any fuel system boiling mitigations or insulation applied?
I believe part of the reason this is cropping up for you this year might be related to the recent EPA decision/waiver as a result of the Iran situation to allow cheaper winter blends to persist through summer. Winter blends have a higher Reid Vapor Pressure (RVP) by design, to facilitate ignition in the cold of winter. That same formula in summer creates more volatility and more load on EVAP systems. Combine that with a rig that traps more heat with skids, but also has increased fuel thermal loads due to the LRA placement in proximity to the muffler, can lead to fuel boiling issues that overwhelm the EVAP and engine. It might be liquid fuel going into the purge valve for which the manifold will not flow evenly as it was designed gasses.
Addressing points others have brought up
- No, fuel fill level generally does not affect RVP. But it can affect how much heat the fuel system can sink from heat sources before increasing in temp significantly and boiling. So more fuel may allow the fuel to stay cooler longer before its heat soaked.
- IMO, the return fuel system being hot is a red herring. That's always been accounted for in the system design. It's mods that add to the heat load of the fuel system that overall creates issues.
That said, there's documented effective mods around the fuel system, tank, LRA, and even the return system that works. I no longer have fuel boiling issues (at extreme elevation).
I don't believe you're wrong that the flooded canister is a result and not the root cause, though I do believe more careful use of the tank could have at least pushed this problem further out if at all. That said, my first priority was always figuring out the immediate why of the codes--if this really proves to have been flooded canister, excess fuel, etc then that problem is solved and I can now worry about the rest of it. But I'd be lying if I didn't say the unnecessary stress of that first phone call saying blown head gasket, chasing the codes for a week and the general unknown and rollercoaster of the last 10 days had me more in a tunnel vision of just getting it back running and understanding what specifically failed. Once it comes back I can focus on preventative measures. Todays first drive showed positive signs, but for now I'm still holding my breath a bit making sure something more sinister still doesn't pop up.
Edit: Man I was just skimming through the mitigation thread again and I even posted in there when I boiled gas. I guess both times that were really bad when it came out of the cap were before I had the LRA. The other time when I just heard it was after the LRA
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That is rough. And was potentially incredibly expensive vs a charcoal canister. We all get things wrong, especially looking at so many different vehicles each day. The vast majority just want to do their job well, which is to diagnose and fix your broken thing.
I suggest this tech was under experienced and/or maybe they didn’t ask a couple of other techs to take a look, which I have zero shame admitting has saved my ass too many times. For something as expensive as that kind of job, I would have to be dead certain that was the problem before having the advisor call you. Because if that repair doesn’t fix what I said it would fix then it’s not good for you, the dealer, or me.
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- #135
Well it’s home—they had driven it twice today for about 30 min each time and I did a 20 min test drive before I left. Immediately following spent an hour getting home fighting rush hour traffic. It drove great, no issues—had a chance to really hammer it during the test drive and I’m sure things started warming up in the bumper to bumper. So far so good so crossing my fingers we are through with that saga. If so I can now focus my efforts on preventative measures so we don’t end up back here again. A small part of me feels a bit of relief, but another part is waiting and expecting the CEL to come on again. Will put a couple thousand miles on it over the next couple months to get some confidence back in it before CROCKIES in July.
Sorry to bird walk but what happened to that door??b
ohh see you there!
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- #138
Trail scar—big ass rock covered by overgrown grass that I didn’t see, and a deep rut that let the slider slip under it