Gas Tank Venting Issues - Have to fill very slowly

[killswitch engage]

Hi,

I have an issue with my 2012 where I can’t pour gas into my tank very fast. If I pour it in slowly it will go but if I try to pour in at a regular speed it overflows out the filler tube.

The truck runs great. No issues, no bog, no DTCs.

I’ve done the following checks:

1. Confirmed filler tube was not blocked.
2. Confirmed filler tube vent hose was not blocked.
3. Confirmed the tank check valve on the filler tube was not stuck or blocked.
4. Confirmed the line from the tank vent to the Evap Canister was not blocked.
5. Confirmed the Evap canister was not blocked.
6. Confirmed the Evap solenoid to open air line was not blocked.
7. Confirmed the line from the Evap Canister to the Vent Purge Valve in engine compartment was not blocked.
8. I checked the operation of the Vent Purge Solenoid – it was normally closed and opens when 12V is applied.
9. I checked the operation of the Evap Canister Vent Solenoid – it was normally open and closes when 12V is applied.

Can anyone confirm the operation of the Vent Purge Solenoid and Evap Canister Solenoid are correct?

Can anyone confirm if the tank vent can be replaced separately? I’m going to check that tonight and see if it’s venting (green valve in picture).

Does anyone have any other suggestions?

I would expect a DTC if anything was wrong with the Evap system, but I have none and the lines don’t seem to be blocked by debris.

 

[ogdobber]

Sounds like the canister is full of gas and thus can't vent the air through. (Usually happens from topping off)


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[killswitch engage]

Sounds like the canister is full of gas and thus can't vent the air through. (Usually happens from topping off)

I removed the Vent Solenoid and blew air through the Evap Canister (with my mouth) and it comes out at the solenoid vent location (see attached pic).

To me, that would mean the charcoal is not saturated with gas. Also, if it is saturated with gas and not allowing the air to vent, I should get a DTC from the pressure sensor (I would think at least).

The problem also starting after putting in 5 gallons of gas when I was on a 1/4 tank. Not full.

 

[ogdobber]

I removed the Vent Solenoid and blew air through the Evap Canister (with my mouth) and it comes out at the solenoid vent location (see attached pic).

To me, that would mean the charcoal is not saturated with gas. Also, if it is saturated with gas and not allowing the air to vent, I should get a DTC from the pressure sensor (I would think at least).

The problem also starting after putting in 5 gallons of gas when I was on a 1/4 tank. Not full.

View attachment 127502

I'm not sure how the whole evap system works, but the fuel nozzle opens the filler so that also opens the vent. To get the fuel in you need to get the air out. That canister should vent to an (open) fuel filler. So leave the solenoid in because that is for something other than (key off) filling. So check by blowing where line 4 hooks up and have the filler open


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[ogdobber]

For filling, the canister should be open and free flow from 4 to 6???


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[killswitch engage]

For filling, the canister should be open and free flow from 4 to 6???

I checked from 4 to 5 --> 5 is the vent to free air. 6 is the line to the Vent Purge Solenoid on top of the engine (which is closed).

 

[ogdobber]

I checked from 4 to 5 --> 5 is the vent to free air. 6 is the line to the Vent Purge Solenoid on top of the engine (which is closed).

5 is to free air but opened by the solenoid (so thats going to but closed when the key is off and filling). You need to check the vent that goes to the filler. Is that 7? And then the canister should blow though (4 to 7)
Keep in mind its mechanical when you fill up. Meaning the the fuel nozzle opens the filler flap but also opens the vent... which comes from the top of the tank (4), to the canister, then up though (tbd) maybe 7 if 6 is going to the engine


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[ogdobber]

This line, not sure where it hook in, but that vents the tank


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[killswitch engage]

5 is to free air but opened by the solenoid (so thats going to but closed when the key is off and filling). You need to check the vent that goes to the filler. Is that 7? And then the canister should blow though (4 to 7)
Keep in mind its mechanical when you fill up. Meaning the the fuel nozzle opens the filler flap but also opens the vent... which comes from the top of the tank (4), to the canister, then up though (tbd) maybe 7 if 6 is going to the engine

Thanks for all the feedback.

5 is to free air but the solenoid is open with the key off (at least when I tested on mine).

The filler tube vent is connected to the green tank vent in the picture in the first post (orange circle on the below pic). It tees off and runs along the tank and is line 4 above when it gets to the Evap Canister (see below pic again).

7 is the front fuel line to the fuel rail.

I would have thought that there's no mechanical interlock/permissive that happens with the key off. Just needs to vent out the green tank vent and into the filler tube vent line. I checked the filler tube vent line and it was clear.

Maybe it's the green tank vent?? I'll test tonight again but I thought air was venting out it (I could be wrong). I'm not sure if it can be removed or replaced even??

 

[ogdobber]

Thanks for all the feedback.

5 is to free air but the solenoid is open with the key off (at least when I tested on mine).

The filler tube vent is connected to the green tank vent in the picture in the first post (orange circle on the below pic). It tees off and runs along the tank and is line 4 above when it gets to the Evap Canister (see below pic again).

7 is the front fuel line to the fuel rail.

I would have thought that there's no mechanical interlock/permissive that happens with the key off. Just needs to vent out the green tank vent and into the filler tube vent line. I checked the filler tube vent line and it was clear.

Maybe it's the green tank vent?? I'll test tonight again but I thought air was venting out it (I could be wrong). I'm not sure if it can be removed or replaced even??

View attachment 127512

Ok so the vent ties into the solenoid line (which is open key off) are you checking the vent line with one of these to hold the flap open?


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