Never seen fuel boiling out the side of the vehicle, but I have definitely overfilled my tank many times before I knew any better and who knows before me.
I did a test to block the purge valve. This only account for +-1.5% or so, and is symmetrical for both banks. My fuel trim issue is bad on both banks, and severe on bank 2. It did appear when blocked, that it was richer (STFT went further negative) than when unblocked (STFT went further positive). I would expect this mix of fuel vapour and air to be slightly rich when unblocked but I have no baseline to measure off.
Would it be fair to say any EVAP issues we could regard as negligable? Because here be dragons perhaps that I’d like to be able to disregard...
one charcoal canister is located behind drivers side mounted to the chassis in front of the tank. The other which is supposed to be fitted with the longranger fuel tank in the rear quarter panel I cannot see, so its possible that’s never been fitted, and the fuel tank is oversized for the single canister.
Here is an example of whats typical positive pressure whenever I open the cap for my 273L tank after a few hours on a warm day -
Not sure if that amount of pressure is problematic, let me know your opinion.
There is some gunk around the fuel cap, its been cleaned we can tell.
If there is a blockage in the charcoal canister, why would that make the system leaner by a few percent? Shouldn’t we just have vacuum if that was the case?
I've done tests with and without the fuel cap and it has made no difference too. Only theory there is if it is higher pressure than normal, it could perhaps cause cavitation for the fuel pump or something like that I wonder, it may have permanently damaged the fuel pump. Still waiting on my fuel pressure gauge.
In any case, if theres some issues here in the EVAP system, I hope we can possibly disregard them for now as they don't appear to contribute significantly to the fuel trims, but perhaps something for preventative maintenance in the future if you think my observations are correct.
I’ve read the manual and I know idling isn’t good but its not like that often and when its really hot occasionally its gotta be done or my dog would not survive.
Disconnect EVAP and plugging inlet of vapor (VSV) to intake manifold. Your, fuel mixture, became leaner (STFT negative). Indicating no vacuum leak in EVAP at time/idling.
STFT, is current engine fuel mixture, expressed as a percentage. It is what air to fuel mixtures is. Unlike LTFT, which is what ECM is doing to correct, to get STFT to baseline near 0%.
If you did indeed, plug the air inlet side of EVAP VSV (Evaporative Emission Control, and VSV stands for Vacuum Switching Valve). This kept, any engine vacuum from from sucking air into/entering intake manifold through VSV. You reduced fuel vapors from air intake (less fuel in mixture). Had you had a vacuum leak in EVAP line coming to engine. Disconnect hose and plugging inlet of VSV. Would have stop, the vacuum leak. STFT would have gone positive (rich). So it does not look like a vacuum leak from EVAP system going to engine intake.
Gas cap sound to me like, opening it, tank suck in air. Which is vacuum in tank. Was it?
I do see some muck in gas cap area, but most cleaned away. The cap letter I couldn't see hardly any, but I barely got a glimpse. Cap did look a bit nasty. Excessive fuel vapors, indicates pressure build up. This is most often caused by a clogged charcoal canister. Which on hot days get even worst.
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I replaced a CC in and 07LC with only 24K miles on last week. No DTC (codes) just suspect clogged CC, for few reasons. Failed emission test in 2022, with report OAT for day high of 92F. Gas cap area and inside cap curdy/mucky and cap letter mostly gone. Idling a running "a tad" rough.
I check weight of new CC, and old CC as they come out. Anything above weight of new, is saturation in charcoal. Worst I even found was 25os overweight.
This one was 22.6oz overweight. All I found with overweight, had no EVAP DTC (code). All had engine running issues. The worst is alway when climbing high altitude mountain passes. But at ~25oz over, even city driving on warmer days, engine barely ran, when stop at a red light in D it would even stall. FT where not as lean as your, but lean. They did improve.
Number one cause is over filling fuel tank, at pump. But just filling with cold gas on hot day, and parking. Fuel may expand into CC. Ascending a rock pass, same results. CC in back near gas tank and nears same level is a poor design.
I'm not saying you CC, is cause of your lean condition. But you now check all possible vacuum leaks. This points to fuel restriction. It is possible a ECM issues, but those are less likely IMHO. So, a fuel pressure test and some kind of flow test is in order now.
It is looking likely related to CC and fuel tank configuration. Which CC do, tend to act up even more on hot days.
Your, one bank more lean than other (LTFT high). Very likely, compression balance variation from cylinder to cylinder and BK1 vs BK2.
Could also have some fuel injector, variation of fuel volume and spray pattern.
This 07LC w/24K Charcoal Canister (CC), was saturated at 22.6oz overweight.
Notice most letter on cap gone. Cap area mucky/crudy. Sure sign of a fuel take excessive pressure from clogged CC.
Looking in fuel fill tube.
Just pass the two air vent holes, just a little deeper in fill tube. If tube relief tube to/from tank.
Travelling further down into fill tube
Fuel filter backflush
P/N for Charcoal Canister in the US 100 series 06-07 is; 77706-60030, new weight is ~88oz (US standard weight).
If you pull your CC to weight or R&R. Be careful with red locking clips. Each side has legs with hook at open end (out of sight), they need to be spread outward, when pulling clip to unlock. Or the plastic hook on leg may bust.
