Recently my check engine soon light came on, a friend of my brothers is a mechanic so he plugged in the computer and it turned out the problem was my “EVAP Canister Vent Control Valve (Close)” He does not work with Nissan’s (I have a 98 Nissan 200sx) so he was not to sure what it meant
Since this was an emmissions thing I did not worry much, but now it seems that I can’t fill up my gas tank properly, even when it’s bone dry, the pump autopmatically shuts off as if it is full. So I end up giving this gentle fraction of a squeeze and it just barely trickles out. The result is that it takes me eons to fill up my tank. Is this going to lead to a bigger problem? How necessary is this to be fixed? Would I be able to pass inspections?
That’s weird. I can’t imagine why that would happen, unless you’re using the same pump all the time. The dispenser nozzle has a small hole in the end of it that basically senses air pressure. When the fuel fills enough to cover that hole, the air pressure change shuts the pump off. I can’t think of a single thing that might be wrong with your car that could cause this.
I would suspect there is a relationship. The CEL is indicating a fault in the evaporative control system. Among other things, this system controls venting of the gas tank. If the tank isn’t venting properly, pressure build up in it is likely triggering the nozzle to shut off.
This problem could end up affecting performance. While I don’t see how it could make the gas tank explode, it’s not out of the question that it could damage the tank or something related to it. As to how necessary it is to fix, I don’t really know, but I don’t see how anyone could tolerate spending half a day filling up.
On late model OBDII cars the cars computer has to test the evaporative system for gas tightness.
different car makers do this different ways.
On some cars the sytems puts a small vacuum into the tank, in others the tank is pressurzied. In both types the tank vent (through the charcoal canister) has to be shut off so that the test can be preformed.
If the valve sticks close, or a spider crawls into the end of the valve and weaves an egg case (yes this happened and we had to buy the car back) the system will detect that the valve is stuck in the closed position.
When this happens the system will set a check engine light, and you could have extreme problems adding fuel, as when the fuel starts to flow into the tank the increased air pressure trips the nozzle to off.
It sounds like you guys know more about this than I do. But I still have to wonder how that problem could affect anything with the car and ignition off, which is adviseable in any case. Then the gas cap is removed, which should also equalize the pressure, right?
Late model cars are designed to trap the fumes from the tank during the refueling porcess into the charcoal canister.
This is in lieu of the evaporative nozzles (the kind with the accordian boot around them)
Anyway letting fumes into the air during refueling is a bozo no-no (pure straight smog) so newer cars are designed to trap the vapors on board.
However if the charcoal canister is either plugged, or the valve in the tank it plugged, or the valve for the canister is stuck the vapors cannot escape the tank at normal pressure, so they start to back up the filler neck, and this trips the auto shut off on the nozzle, same as if you had filled the tank.
Rick, I wonder if you work in the same type of field that I do?
parisms, were you in the habit of over-filling your gas tank, i.e., “topping it off” after the pump automatically shut off? I’m not familiar with your car’s fuel system, but I do know that many vehicles’ fuel systems, when “topped off”, are prone to flooding of the charcoal cannister. Then you get all of the problems that you’re mentioning and that Rick explained.
Replacing the charcoal cannister will probably help you. I recommend letting your dealer or a shop do it. Despite being out of warranty, you may want to check and see if these parts are covered by the federally-mandated warranty on emmissions systems, which I seem to think is 10 years – I’ll let you research the truth to that.
Hey thanks alot everyone for the info, I can see now how the correlation would be possible. Rick you really seem to know your stuff. I’ll probably call Nissan today and see if they can fix it.
Balthaisar, do you know where I would look to see if it is covered by the warranty?
Balthisar I don’t know. I left my crystal ball in my other pants so I don’t know what you do. I’m a technical training instructor for a car company, what do you do?
As for the flooded canister, that too is a posibility. It did not occur to me, as I have come across one of those in a very long time.
for the emissions warrenty check your owners manual.