I found out something interesting about fuel systems today. My wifes car had a check engine light on and we took it in for service. The problem was that the charcoal canister had deteriated and had "spewn" charcoal thruought the entire fuel system. Paid $110 to have the fuel tank dropped and everything all the way up to the fuel filter blown out with air and replace the charcoal canister. What I found out is that I am the probably the one who caused this. How? By overfilling the gas tank. I like to top off the tank all the way up to the top of the filler hole. Lesson learned=$110. I do have one question though, is the fuel system on the Maxima (My wifes car is a mustang) prone to the same problem? (I did this on both cars) Should I be worried? Should I replace my charcoal canister now before it fails and causes problems? I just thought that this would be some good info in case anyone might have the same habbit as me, it is not worth the few extra miles you might get.

 

that is seriously some gas stations even do that, so in my opinion thats sh!tty build quality on fords part.... but hey who am i to judge i dont even know wat a charcoal canister is

 

Our car are not like American's.. We're not prone to dumb issues like that

 

i do the same, i fill my tank all the way up. i even shake the car as it fills to the top.

 

i have a 3rd gen. if i fill my gas to the top, ie, overfill it, there is an overflow drain on the filler pipe and gas leaks out of that. i discovered that one day when i saw gasoline pooling and dripping under the car when i came back out of the store. i was taken aback by that when i saw it, so i looked closely for where it came from. and i found a little dimple thing on the pipe. and it looked machined or deliberate. so i'm assuming it is supposed to be that way.

what is a charcoal canister?

 

Is the charcoal canister the same as an evap canister?

 

Charcoal canister filters gas fumes I believe. I don't know what that has to do with the gas level. Maybe if you fill the gas level so high it backs up into the gas fume recirc line?????

 

The 5th gen has that too, but it is outside of the fuel cap, ie it has to overflov outside of the fuel filler hose.

I believe that the charcoal canister is the same as evap canister. Here is the "ford" definition of what it does; "...holds fuel vapors until certain conditions are sufficent and the purge valve is opened and the fuel vapors are consumed in the normal manor of fuel." I don not know what those conditions are so I don't know what sets it off.

I believe that what happened is that fuel did make it's way into the canister and destroyed it from the inside out, hence charcoal thruought the fuel system.

I just want to make sure my Maxima won't develop the same problem.

 

Jeez, that's one of the more ignorant posts I've seen in a while...and that goes for all you "domestic" bashers (not just the dude I quoted). All new(er) cars recirculate their gas fumes through the evap cannister/charcoal cannisters, and the draw vent for part of that system is in the fill up spout for the gas tank. If you overfill the tank/neck all the time, then it sucks in liquid gasoline instead of just gasoline vapors. It's also why your manifolds/plenums get dirty as hell over the course of several thousand miles (as well as TB's and injectors). That recirculation system dumps that **** into the fuel/air mix pathways (different places for the dump for different manufacturers) so it can burn/re-burn those fumes to help with the overall vehicle emmissions. Gasoline will eventually break that charcoal down, and it will send it all over the damn place in your engine and fuel system. It makes sense when you follow where all the tubes for the system are routed/connected.

OK, enough b!tching on my part. Lesson learned is that you NEVER EVER overfill/top off your gas in newer cars. And yes, the same **** could happen to the Maximas...

 

Actually, your intake manifold/tb get dirty becuase of the EGR system, not the fuel vapor recirc system.

 

It's the same system on some vehicles. That's why I stated that it dumps it in different places for different manufacturers (forgot to state that it's the same system in some as well). I can't say for certain if the fume recirculation is part of the EGR system on the 5th Gen Maximas, but I guess I could find out by taking it apart when my wife gets home...

 

IMHO. If you disconnect the fuel vapor return system, the manifolds will still get gunky. If you disconnect the egr system, the manifolds will stay clean(but you car will run hotter). In my 3-gen, the egr is not part of the fuel vapor return system.

 

Unfortunately, it is on my damn truck! My upper plenum gets dirty as all get out. There's even a line from the oil fill up spout to the back of the intake (plenum). Hell, hold on, I'll go take some pics and show you what I'm talking about...

 

This is the connector at the back of the upper plenum (intake) that goes to my oil fill up spout.

 

Here's a little pull back on the same area...

 

This is the part that connects to the valve covers/heads and dumps via suction into my OEM filter box on my truck...

 

Here's where part of the system runs to the vac booster, and from there to my upper plenum (intake...the composite thingy)

 

Here's the fill up spout (seen from under the spout, just before the fuel tank).

 

Here's where it breaks off and feeds into this "thing" under my truck (approx. midway on the left hand side, underneath...)

 

Here is the connection side of the "box thingy" under the truck, which then head to the engine bay...

 

Here they are running to the engine bay on the LH side (underneath) the truck...

 

And finally...into the engine bay (LH side; underneath) in the vac booster (which if you remember from my posting about 10 miles back) which goes directly into the upper plenum (intake...composite thingy)

 

I'll get a pic of where the booster to intake part meets if you want It's all one big happy circulation system, and I'm pretty positive that most, if not all, cars are designed this way.

 

Fuel evap system does not cause the manifolds to get dirty. The positive crankcase ventilation and the exhaust gas recirculation systems are the cause. The pcv puts blowby into the intake and the egr puts exhaust gas into the intake. Those causes the carbon and other junk.

The evap stores the gas vapors in the canister. During certain conditions like cruising at highway speed, the engine vacuum will pull the gasoline from the canister. Gasoline will not gunk up the intake, but will actually help clean it because of the detergents that are in it.

The vapor gas in the evap canister will turn back to liquid form once it cools down. So it is normal for liquid gasoline to be in the canister and should not cause it to fail. The bad thing about over filling is that when the canister is full, the gas has no where to go but into the intake causing it to run rich.

 

Ahhh, you'd like to think that, wouldn't you. There is no PCV valve on a 2002 Dodge 4.7L V8...

 

a 2002 with that much rust/rust-residue? Holy cow man - where do you live?

 

The pcv system does not always have a pcv valve.

 

That's not rust It's Georgia red clay, and I have had my truck in the mud a few times. It's kinda part of my job...

 

And like I stated...the fuel evap cannister dumps it's line right at the TB, so yes, in this case it does indeed cause some buildup/gunk. If you saw where it hooks up, you'd understand...

It's a well known issue with the 4.7L guys.

 

Thanx for all the info. I am no longer going to be filling my car up to the brim anymore. I just hope that I did not cause any damage by overfilling my car. I will look under my car tonight to try and understand how it works some more. Thanx again yall.