Full Tank Noise?

[ovrlnd]

Here's my theory. The fuel system is closed loop. To comply with epa reg. (Not sure how many of you own old cars but when you overfilled those the vent would spit the gas onto the ground.) Back to the raptor, there has got to be a vent that goes to a part of the intake... And if you give a couple clicks of the handle when filling after it clicks off.. It pushes a little bit of fuel up there and you get a "rich" backfire when it is burned off. If you where watching the afr when the truck backfired you could see this.
Fix- when the nozzle clicks off, that's it, you are full


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I'd think if this were the case, then you'd get the same problem from fuel sloshing around the tank even when not completely full. You'd also see the same thing on regular F150s. More likely some error with the evap system/valves.

 

[ogdobber]

I'd think if this were the case, then you'd get the same problem from fuel sloshing around the tank even when not completely full. You'd also see the same thing on regular F150s. There should be a check valve that prevents this from happening. Maybe it's a bad valve?

You are not going to slosh fuel uphill all that way. But with pressure... You could get it. Why not regular f150s? Is say it's something to do with the ho Ecoboost that only comes in the raptor.
Curious to know if the op gives a couple extra clicks, or anyone else that has experienced this.


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[sp2pilot]

I just filled up a few days ago. $72 dollars worth, ouch. Never heard the sound that you guys are describing.
Once the handle clicks, I let it sit there for a few seconds before removing it. I never try filling it more to top it off.

 

[ovrlnd]

You'd have to push enough fuel to fill the evap can before it made it's way to the engine. I do suspect it's something similar, but I suspect that it's an electronics problem rather than physical. Something in the pcm not sensing the correct pressure or fuel level or something; i.e., when the purge valve opens after the engine is warmed, there's more pressure in the evap system than it's accounting for.

edit - remember this guy who sat at the gas station for two hours trying to see just how much fuel he could squeeze into the tank? http://www.cleanmpg.com/community/index.php?threads/51614/

 

[Azholley]

You are not going to slosh fuel uphill all that way. But with pressure... You could get it. Why not regular f150s? Is say it's something to do with the ho Ecoboost that only comes in the raptor.
Curious to know if the op gives a couple extra clicks, or anyone else that has experienced this.


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I've never put in extra or topped it off and it still happened to me 2-3 times [emoji848]


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[ogdobber]

I've never put in extra or topped it off and it still happened to me 2-3 times [emoji848]


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Interesting. Well in California they limit the fill rate to 10gal per minute. But in other states, at a station with high fill rate/pressure might do it on initial shutoff. What state are you?


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[Azholley]

Interesting. Well in California they limit the fill rate to 10gal per minute. But in other states, at a station with high fill rate/pressure might do it on initial shutoff. What state are you?


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Arizona


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[pjones]

When you overfill your tank, the extra fuel is sent to your evap canister. I am still unclear as to why you think this will cause a back fire...

 

[Azholley]

When you overfill your tank, the extra fuel is sent to your evap canister. I am still unclear as to why you think this will cause a back fire...

I'm not convinced it's a backfire either. Sounds like the rear end is shifting.


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[jes.jr]

Same thing here. First fill up, never heard it on my 13. It sure sounded like a bang rather than something shifting in the bed.