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Dodgerench, ASE Certified Technician
Category: Dodge
Satisfied Customers: 3404
Experience:  30+ years Dodge/Chrysler exp., ASE Master with L1 certification. Driveability/ combustion specialist
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2007 Dodge Dakota , the problem is the fuel tank is pressuring

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2007 Dodge Dakota , the problem is the fuel tank is pressuring up like the vent tube is plugged. I cannot fill the tank without filling it very slowly because the air is flowing back up the filler neck. The service engine light has also come on. Just prior to this problem I did get the truck quite muddy in a large water hole so I am wondering if the problem may be from mud or water getting somewhere it shouldn't be. Or maybe from when I washed it including under the hood. I would really appreciate any ideas.
Hi Customer, my name is Ed. Welcome to Just Answer!.

You guessed right! Fuel tank venting is a little lower on the 07 models than what's practical for anything that goes off road or gets somewhat submerged. The vent tube connects to the inner left frame rail at about the location of the driver's door handle area and then runs back over the top of the tank. Look for the 1/2" ID hose that seems to dead-end at the frame rail and that would be it.

I'm expecting that water is the actual cause for your suffering though. Mud is mostly excluded from this vent system, but there is nothing to prevent water from backing up the vent tube to your vapor canister... flooding it... and blocking tank vent flow. Lowering the tank to remove and replace the vapor canister will be required. Even though the canister might some day dry out, the effects of dirty water entry won't disappear.

This situation probably calls for replacement of the ESIM (evaporative system integrity monitor), which may or may not come with the vapor canister. Its job is to monitor the evaporative system for leaks, with the vapor canister storing fuel vapors that occur during normal operation and during fuel fill operations. The ESIM likely got a snootfull of water and crud, so it's a gonner... the reason your CHECK ENGINE lamp is on is quite likely from failure of the ESIM.

I've seen instances of lift-throttle stalling and related evap system failure codes set from water being drawn out of the canister to the purge solenoid underhood, which can then stick open. Your purge solenoid and purge lines need to be inspected for water aspiration and for proper sealing of the solenoid when de-energized.

Aside from the time and expense of replacing the canister-ESIM assembly and the purge lines/ hoses, the repair is fairly simple. Clear your PCM memory after repairs by performing a 30-second battery disconnect and you should be all good.

Dodgerench and 4 other Dodge Specialists are ready to help you
Customer: replied 6 years ago.
First of all thank you for the quick response, I have called for pricing and availability on the parts $ 176.00 ( could be worse ) however I am looking at about 1 1/2 weeks to bring it in as they are aparently on back order ( I must not be the only one who mistakenly thought I could actually use my 4 X 4 offroad ). Is it ok to continue driving the truck in the meantime or is there any way that I could clean the canister? I can get the ESIM right away.
The only real damage I can foresee is with the purge solenoid if it hasn't been contaminated already. The small quantities of water that get sucked through the purge solenoid into the engine shouldn't hurt anything since it's split so many ways once it reaches the intake manifold. If you would like to disable the purge solenoid, this is what you'd do...

Locate the solenoid, which is positioned just inboard of the brake booster. Two rigid vacuum tubes will be involved, as will a 2-wire connector facing the booster (driver's) side of the unit. Click the red slide-lock to its opposite position, then press the release tab and pull on the connector. A P0443 code will be set, but you're already used to seeing the MIL turned on. No biggie.

After lowering the tank, remove the rigid lines from the purge solenoid and vapor canister and blow 'em out with compressed air, then reconnect. You should be OK from there unless the solenoid is contaminated and continues to leak vacuum in its closed (de-energized) state, in which case you'll continue to set evap leak codes. A purge solenoid will almost certainly be needed at that point.