Troubling p0456

9911 Views 10 Replies 6 Participants Last post by  guy65
Have a 2008 Ram 1500 with 5.7 L Hemi

Truck keeps throwing p0456...

There is a new mopar gas cap...
The truck was smoke tested...nothing
Was told that purge valve was ruled out.
I've also changed the EGR Valve twice now and the PCM last year because it was malfunctioning, i.e. burnt 4WD and likely the EGR too.

Something of interest, when the tank is filled, it almost always spits gas - even when filling on slowest setting.

I need to pass emissions and need to hopefully resolve this without lots of expensive exploration. Anyone have any thoughts or does this sound familiar?

Thank you.
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ncoppola- it's the evaporation valve. it sits usually directly at the fuel intake underneath. it's actually just a simple pipe with a ball in it. the gravity pulls the ball down and closes the pipe. if the airpressure increases in the tank, for example when you get gas, the air pushes the ball up and the air comes out there. the hose routs to the front to the active charcoal filter- there is another solenoid valve. one or both can be broken. that's usually the reason for spitting- the air can't go out fast enough and the backlash pushes the gas back out.

What I think about smoke don't wanna know.
sometimes they either clog up or just stuck. There is also a similar cut off in the snorkel to the tank, which actually suppose to lock, when the tank is full, to prevent the gas from squirting out.
just a simple question- when you drive and stop. cut the vehicle off, like when you get gas. if you remove the gas cap- do you hear air flow? this is mostly a sign- but you would have to do it immediately after turning the vehicle off, because if it's too long, the pressure goes away slowly. usually there should be no pressure or vacuum.
The ball valve is hard to get to, because I think it's imbedded into the snorkel assembly.
What you can do- and I don't know how much technical equipment you have- if you have a air compressor, take a rag and the air handle and blow air in it, while you close the gap around the handle with the rag- but don't increase the pressure too fast. do it slow. this usually looses the ball and blows the dirt out. Another thing- check at the active charcoal filter, if there is a solenoid valve- pull the connector off and take 12 v and ground wires (best is if you would have a pigtail but if you're careful, you should be good). there should be only 2 pins because it's just a open/close valve. attach the + and tip the ground to the other pin and hear if it clicks. also- if you pull the hose off, yeah- little tricky- you might need 2 people for that- one blows in the tank, the other switches the valve and see, if the valve opens and closes and if air goes through and stops, when switched. that's pretty much all you can do. there is not more to the system.
And I be honest- I never done trouble shooting for that on a RAM, because I never had the issue. I can't tell you where the valve is, but it should be there- either directly at the fuel snorkel or right at the active charcoal filter. as far as logical positions.
If your error code is Gas Cap, that's where you got to check, when the gas cap is ok.

Here a link to some pictures- you should be able to find it with this:******************%25252Fforums%25252Ff170%25252F2004-dodge-ram-hemi-1500-vapor-canister-fuel-issues-11897.html&source=iu&pf=m&fir=9o8RAIDO6MCOgM%253A%252Cut9XAPPSnfiC9M%252C_&usg=__2lp3GyrVEqZvTzAAGy4CqT5yzkI%3D&ved=0ahUKEwjt8LC2sbnOAhVGbSYKHShnDCkQyjcIKQ&ei=i3KsV63_CsbamQGozrHIAg#imgdii=9o8RAIDO6MCOgM%3A%3B9o8RAIDO6MCOgM%3A%3BCHF_C6m3qYh2RM%3A&imgrc=9o8RAIDO6MCOgM%3A
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seems like there is a problem with your tank evaporation. can have multiple reasons- either it's the ball-stop at your nozzle which routs the fumes to the charcoal filter or it can also- how you described- that the ball, which floats under your filler nozzle gets clogged up and stuck. the ball is there, if your vehicle turns over, that the gas tank does not run out. you might be able to get to it, when you get your tank out and reach through the hole for the pump. sometimes this happens, when the evaporation valve does not work and the tank gets a vacuum and compresses. How you say, it seems like this is your problem. The clicking, what you hear is likely the soleonoid valve for the evaporation line, which actually closes the line, when the engine is cut off- the sensor recognizes, that there is no air flow and tries to open the valve, which is already open- it will be tacted. Check your evap system. But if you rather ask, instead of try, what people tell you, there ain't nothing anybody can help you with.
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