Evap codes and gas problems
 

Hi guys, sorry this might be a long post but I appreciate you reading it and giving me advise. A few weeks before Christmas 2016, I went to the gas pump to fill up. The pump shut off repeatedly and I couldn't get more than a few dollars in. I tried moving to a different pump at the same station and the same thing happened. I left there and went to a station closer to my house and the pump filled normally and I was able to get a full tank. A few days later my CEL came on and the code was P0456. Naturally I did forum and google searches and Decided to change the gas cap. I bought a Gates from Amazon and installed it. Maybe a day later, my tank wouldn't fill again at the station I previously had luck at, and this time my CEL was still on as well as the gas cap indicator now visible.

Deeper internet searches told me to check hoses and charcoal canister. First thing I did was disconnect the hose at the canister that runs from the tank. Went to the station to fill while it was disconnected....no luck. I came home and disconnected the filler vent hose from the neck to the tank. It has a quick disconnect on both ends so I took the hose off completely. Went to the station....no luck. I felt the short rubber hose that connects the filler neck to the gas tank inlet, it doesn't have any kinks that I can feel. I then took a long rigid polyurethane hose and shoved it down the fill neck to check for obstructions. I was able to poke what I believe is a check valve just inside the tank, I could swear i hear a flapper or something when probing. I then took the truck to the station....It filled completely.

The next 3 fill-ups went fine, even thought the CEL and gas cap light are on. But this past week, I went to the pump...no luck. Just clicked off after less than $1, almost like it just fills the neck up and shuts off, then slow drains into the tank. So I grabbed my trustly polyurethane hose, poked down there and felt that flap give way, drove to the station....success again at the pump. But this is going to get old and Im slightly afraid of future problems it might cause.

Currently I have 122k miles on the truck. It is a 2011 Ram 2500 Hemi with the 32 gallon tank. I have never that I can remember, topped off after the pump shut off. My current codes are p0440, p0456, p0457.

get to the nearest garage with a smoke machine and pay for the diagnostic. You most likely have a leak somewhere.

the esim vents the tank during refueling. It also seals the evap system. the code that set is small evap leak.
there are valves in the tank itself but they are not serviceable...if they need replacement...its a new tank

your probably still underwarranty...let the dealer sort it out.

Doesn't this sound like the tank vent is clogged? I've seen this on a number of GM cars and one Hyundai and in all cases it was a clogged vent.


Regards,
Dusty


2014 Ram Big Horn 1500 Quad Cab2WD, 5.7 Hemi, 8HP70, 3.92 LSD, factory dual exhaust, 20” wheels. Now at:050943 miles.

the valves in the tank are for roll-over shut off and another to shut off the gas pump at the filler neck.
the line from the canister to the tank...you unplugged at the canister but did you make sure the hose to the tank to the canister is clear?

since jamming something down the filler neck allowed it to refill...maybe it was the internal tank valves.

i worked for gm for 10 years....completely different evap system...usually its a bad vent solenoid for gm's when the tank won't fill.