Trouble w/evap system that no one can seem to solve

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AcworthGuy

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Ram Year
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Hemi 5.7
Hey Everyone,

I've reached the point of where I'm about to sell my '09 Ram 1500 Laramie (5.7) because of an ongoing problem I've had for about a year. I don't want to do that, but I’m close. Here’s what’s happening...

It all started with a loss in power and gas mileage. The truck runs like the tires are under-inflated by 10-15psi - it’s very sluggish, especially at low speeds, as if I’m pulling a heavy trailer. When I first touch the gas, it hesitates greatly. It takes ~1.5 seconds for it to downshift and get going sometimes – VERY frustrating when pulling out into traffic. On top of that it’s averaging ~11mpg around town and highway. I’m currently at 6.5mpg. It used to average ~15.5mpg.

It then threw a 456 ECU code. More on this below. Perhaps the most telling: when filling the tank with gas, once the pump clicks off, gas comes spewing out of the tank all over the side of the truck and onto the ground…a good 1/4th gallon. I’m positive this is related to the overall problem.

The problem comes and goes – during one trip it’ll run fine but the gas mileage may be off. Other times, both are great. However, like clockwork, if I turn it off, start it back up, the problem comes back. Re-filling with gas sometimes makes it worse…sometimes better. A can of Sea Foam treatment in the tank can even help….temporarily. The problem is all over the map but it’s very predictable.

I’ve taken it the dealer twice and two other independent garages three different times. These expert mechanics look at me like I’m crazy when I tell them what’s happening. They’ve told me they can’t reproduce the problem, the mileage looks good, the power seems okay and so on. I’ve even had two different people tell me (including the dealer!) that if the ECU has no codes, there’s nothing they can do to help. Amazing.

I’m a pretty technical guy. I do a lot of work on my own cars and I also race so I feel like I’ve got pretty good sensitivity to something not being right. I’ve taken things into my own hands to the greatest extent possible. I know without a doubt that there’s something askew in the evap system.

Here’s what has been replaced:

·Spark plugs and air filter (thought this was the problem early on)
·Throttle body (dealer, waste of money)
·ESIM (dealer, this fixed my 456 codes)
·Purge solenoid (self-installed)
·Purge valve (self-installed)
·Gas cap (two different ones, one Gates and one Mopar)

A smoke test revealed no problems. That mechanic said my lockable aftermarket Gates gas cap was the problem…New Mopar cap made no difference.

An acquaintance recently suggested that it could be the evap canister has gone bad. I haven’t replaced it because it’s so hard to get to but I'll pay someone else to do it if I need to. This guy also said the overflow tube from the filler neck that goes back to the tank could be clogged. Perhaps even the filler neck is bad or the tank is not venting properly.

I think this is a mechanical problem but could it be the ECU is malfunctioning??

I feel like I need to take it back to the dealer. They’re going to know the truck the best and be able to get the factory on the phone if needed. But I’m so down on dealers (both in my area stink out loud) and, as you know, all those trips are so time-consuming and such hassles that I’m starting to think I just need to sell my Ram and get something else. But I don't want to do that...

Thoughts anyone?
 

baulet

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first, to fix the gas tank pb... maybe a valve somewhere? evaporator circuit clogged?

after, i think about a defective transducer, or wiring...
check the plugs for oxidation?

last, if possible, it is to re-flash the ecu?

good luck!
 
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AcworthGuy

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Hemi 5.7
Thanks Baulet...going down this path now. I just confirmed that my ECU was actually replaced during one of my visits. I just got the latest firmware updates as well. Standing by.
 

baulet

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YW,

so for the ecu its a good thing.

your pb of overfilling looks like a "belier" symptom: a pocket of air somewhere is compressed, and when realeased, it push the gas out to the filling gap.
in other words, some pressure is accumulated somewhere when you fill gas.

it could be the vapor canister, or something foreign in your tank?

for the rest (and not the least) i thing to an electrical problem.
the ecu send by moments to much gas, so look at the sensors.
cold air and/or hot gas = more gas injected
O2 too lean = more gas injected
try to get the wiring diagram of the ecu, to find all the sensors wich could be in cause, i sure forget some.

hope it helps...

courage man!
 
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