Custom fuel filler neck size + angles

[BrettInUte]

Have a nissan patrol GU dual cab cut.
I re-used the original (dual) fuel filler neck, just hung it off the underside of the flat deck steel tray.

But im having HEAPS of issues getting the tanks to fill at a full flow rate.
I cant even consider using a high flow diesel pump.

Ive remounted the fillers 3 times now, each time getting the filler neck angle steeper and steeper.
But still have issues filling.
Diesel bubbles foam up - and kick back the stop the flow from the hand piece.

I have only limited height between the tray deck and the sub tank filler tube - that may be a limiting issue. (maybe 200 mm)
But there should be plenty of height for the main tank.

Im considering getting a single cap - dual filler arrangment like the prados use.



What kind of angle and length do I need to get a full bowser flow going smoothly ?




Cheers.

[Red Dog 4x4]

Check the breather it could be blocked or under sized.

Thats the only thing I can think of.

Red Dog

[BrettInUte]

yeah - Ive rerouted the breather lines too.

but its still a case of "no love"

Im still pretty sure its the shallwo angle of the filler necks causing the problem.


Cheers.

[hiluxmad]

maybe make the filler necks longer and put them further from the tank?
there is no logic behind this just a thought?

[MattGU]

This isn't a long term solution but I had the same problem with my GU. I found a local servo who's driveway was on an side angle. Parked with the filler on the up hill side close to the bowser. Worked a treat.

[norty40]

My sub tank has a filter about 10cm along the pipe and it only allows a trickle of fuel past at a time. Check to see if you have the filter there and that way you can just take it out.

[BrettInUte]

OK - so I remounted the std dual filler necks as high and as far out to the edge of the tray as I could.
(cut most of the metal cup around the filler caps off)

I went to the wreckers and got another set of standard filler neck rubber hoses.

I tried to get the filler necks to be as steep as possible (to try to get the foam away from the pump nozzle)

I had to extend the sub tank rubber hose - with a crafty piece of steel pipe.

Made sure the breather hoses were nice and high and not blocked.

and the result was.....
Main tank fills fine. Can almost fill at full pace for the whole tank.
Sub tank will only fill well if I hold the pump nozzle a long way up the filler neck (still not enough fall here I think). the diesel froth basically covers the breather - so lots of stops while filling.


a partial win...

[V8Patrol]

Had same issues with our old isuzu work truck.... absolute bytch to fill

we left the original filler neck alone but added a new 75mm pipe made from exhaust tube and bent as required to the tank..... the entry point was at the bottom of the tank and was as steep as posiable, added a cap and problem basicaly solved.

we later removed the std filler cap and changed it to a filtered breather
(add some rubber hose to take it away from the tank and a small air filter)



we could fill it with 2 highflow nozzels stuffed into the new neck
took longer to get the nozzels organised than what it took to fill it

[BrettInUte]

added a new 75mm pipe made from exhaust tube and bent as required to the tank..... the entry point was at the bottom of the tank and was as steep as posiable, added a cap and problem basicaly solved.:

So you added a 75mm inlet direct into the lower edge of the fuel tank ?
(and you used the orginal filler as a breather ?)


My tank sits between the chassis rails - so I cant really access a filler point any lower on the tank. (curent filler to top edge)
And Im not willing to go welding the tank (just yet anyway)


I tried to make the filler necks as steep as possible - but Im thinking now - thats the wrong way to go. I should make them as close to horizontal as I can - them rely on the bend in the fuel pump nozzle to get past the first few inches. that would then make the rest of the filler neck even steeper which should help a lot.

Still not sure if the std breathers (in ANY position) are big enough to handle a fast fill nozzle. Id appreciate any advice on that....