Fuel tank inlet question

[kf6kmx]

Not sure if this has been covered before, I tried the search and it gave erros instead of searching

Anyway, I'm wondering if anyone has tried expanding the diameter of the fuel tank inlets slightly, so they accomodate the larger high flow nozzles at truck stops?

My favorite truck stop that I always get fuel at (9 out of 10 tanks are from there), has both the 'automtove pumps', and a set of the 'truck pumps' for diesel. I usually go to their 'auto' pump island, but today it had a large line of idiots (just sitting there talking on the phone and /or doing paperwork instead of pumping) so I headed over to the truck pumps.
He has the high flow/volume truck nozzle.. It works on my '97, but you have to manually hold the nozzle in and only pull the trigger slightly or it will not take any fuel. The nozzle itself wont go in past the little 'ridge' in the tank kneck. Its NOT hitting on the threads where the cap goes, but inner from that slightly, it looks like there is a ring that is restricting inserting the larger nozzle.. Since it isnt a gas vehicle, there is no restrictor for stopping regular vs unleaded nozzles..
Does anyone know if/what the purpose of that slight ring is, and has anyone tried a pipe-expander to see if it can be slightly expanded (only take less than 1/16-1/8 max expansion to clear) to allow the higher flow nozzle? It fills the tank MUCH faster than the auto nozzle, even holding it slightly on, and would be much nicer to use regularly if you didnt have to manually hold it and could let it fill on its own.
Both the auto and truck pumps are pumping #2 diesel, so it shouldnt be to prevent one pump from fitting into the truck, my guess is Ford never thought anyone would want to use the truck islands...

[kf6kmx]

Watching the tank fill with a 'normal' diesel pump it also looks like that little 'collar' in there may be one factor that causes the diesel pump to keep kicking off over and over again... Looks like the fuel may be hitting that a little and foaming/spraying back and tripping the nozzle shutoff..

[kf6kmx]

anyone?

[Gruss]

The problem with using the large nozzles, is that the tank vent isn't large enough to let the air out of the tank fast enough, causing the pump to trip. There is a mod to fix this. You remove the inner hose from the filler neck, and add a vent hose from the top of the tank to the top of the filler neck. You also have to remove the "reducer" collar in the top of the filler neck.

[pjwoolw]

Regardless of the nozzle size. Faster is slower when it comes to pumping diesel fuel. I have found that a nice slow pump is faster to fill up. I usually top off up into the neck. I also complain if the pumps are to fast. But anyway check out transferflow. They make replacement necks.