SamSmurf

Hi, I have a 2021 Motorhome on a Chevy express van 3500 dually chassis with 6.6L engine and 30 gallon fuel tank

I've always had issues filling up the gas tank and the pump would shut off if the fuel pumped too fast. I have always needed to squeeze the pump just enough for a slower flow to not cause the fuel to splash back and turn off the pump.

Today I stick a borescope into the filler neck to see if there are any obstructions leading to the gas tank and I find this white cap with a small hole about a foot into the filler neck. This white cap doesn't look like a flap or a vent and it looks like all the fuel must go through the little hole which may be the cause of why the fuel pump stops so early while fueling.

First picture shows the white cap with a small hole inside the filler neck
Second picture shows the filler neck underneath the RV. The 11 inch mark is most likely where the white cap is located. Basically where the metal tube ends and where the black tube begins

I wanted to ask if any one knows what this white cap is? and if I take it out would it cause a check engine code to come?

Derrick71

I don't know the answer but that does seem like a small hole for all the fuel to pass through. I'm not sure why they would have such a restriction in the filler neck but I'm also not up on a lot of whats happening with newer vehicles either.

I don't see how it would affect pressure or vacuum in the tank so removing it probably wouldn't cause a CEL.

If I were forced to take a wild guess I'd say it was an anti-siphoning screen that didn't get all the holes punched in it or a plug to keep debris out during manufacturing and was supposed to be removed before assembly.

SamSmurf

wow that makes alot of sense.
I'm going to take it out and hopefully it will be easy and wont cause any future issues

Derrick71

Let us know how it goes. I'm definitely curious about it.