Flatbed filler neck solutions

A couple months ago I built a flatbed for my 22' 6ft bed. I reused the stock filler neck, and currently it sits about 3' lower than the stock location with a stock truck bed. For the first 2 months I had no issues with filling up, I was able to lock the pump and walk away until it clicked off. One day the pump shut off almost immediately, and then kept on shutting off every 0.05 gallons. This issue persisted for about 2 weeks, I tried pulling the driver side rear onto a 4x4 block to angle the flat run in the filler neck, but this proved to not help. Miraculously, one day I had no issues filling up and could lock the pump and walk away. This lasted for about 3 weeks before the same issue arose again. I make sure not to overfill to prevent fuel from getting into the vent line or charcoal fuel filter. I know guys running fiberglass fenders use 4 runner filler necks, but other than that I haven't found any solutions. Any and all help would be appreciated. Let me know if you can see my photos.

 

the swoop-down/dip over the frame rail is your issue. the fuel is getting stuck right around the frame rail and the back pressure is kicking the pump off.

you need to have a constant pitch towards the tank for the entire length.

so going through this thread:
https://www.tacomaworld.com/threads...berglass-bedsides-glassworks-write-up.448370/


he's doing basically the same thing i'm describing. his setup still has a kick down just above the frame rail, but because of the other modifications to his setup, the gas cap is at a higher level, so there's less back pressure on the fuel while filling. clearly, that won't work for you, as the tool box is in the way.


at work, i do a lot of ford cab/chassis fuel kits-- i'm not intimately familiar with toyota's setup outside of the pictures i looked at for this thread, but i've done far too many ford kits to count. those are always hose clamped to the tank inlet, and then pieced together with ford-included fuel-rated tubing, and included adapters.

it's basically this kit, plus a few extra hose lengths and metal couplers i can't find online
https://parts.ford.com/shop/en/us/fuel-chassis/chassis-cab-filler-neck-p-mc3z9034c

it also includes this filler neck support, which looks like it would work really nicely in your big fuel opening
https://www.fillernecksupply.com/53...uel-fill-pipe-bracket-housing-ford-oem-angle/

otherwise, if it were me, i would figure out the critical tubing sizes, and then piece together a kit off that filler neck supply company and call it a day.

i don't think it's critical to use toyota-only parts in any part of it.

 

Awesome, I really appreciate the detailed response. I think the path of least resistance for me is gonna be to cut a hole in the bed and toolbox and run the filler neck through the toolbox to eliminate that downward swoop. If that doesn’t work then I’ll have to piece together some hoses like the ones you showed me. Thanks again!