Working on a theory to stop the overfill issue on this tank.
There are two vent tubes that come out of the tank: one goes to the charcoal filler and one goes up to the fill neck. The small one that goes to the fill neck is there to shut off the pump. Inside the tank, where that 1/4” line goes in, there is a tube that drops a certain distance into the tank. Once the fuel level reaches that tube, it cuts off the airflow and that’s what shuts the pump off. Based on the short length of the vent tube and the shape of the tank in that area, the vent tube doesn’t get shut off until the fuel tank is darn near completely full. By that time, the pump has already pushed out enough fuel to more than fill the full neck. So, my guess is that the fuel vent tube that drops into the tank needs to be longer. I’m beginning to test this by making a new vent tube that’s much much longer than the 3” (or so) long one the tank came with. I’m hoping I see that with my super long vent tube, the fuel cuts off reliably early. Then I’ll trim it down until it cuts off reliably at the right time: when the tank is full but not overflowing. It’ll be a long process because dropping the fuel in the tank enough to test will take a little while each time. I’ll be sure to update this though.
Here’s where I’m starting:
I made a slightly longer vent tube and put it in. Didn’t make any noticeable difference. But the tank is usable so I took the vent that came with the tank and cut the extension tube off of the fitting, drilled it out, and used JB Weld to glue in another long piece of brass tubing that I could source locally.
Here it is all glued up and ready for install. This experimentation would be a nightmare with the factory bed in place. But since I’ve put on a flatbed, access to all of the tank fill and vent fittings is unbelievably easy. Hopefully, I’ll find the right length to reliably fill the tank and not overfill. Then, I’ll give you the dimensions and you can make your own vent tube and install it once. It’ll be painful but it would only be painful once.
This could all lead to nothing but I’m keeping high hopes until it proves otherwise. I’m SO tired of not being able to just fill the damn tank like a factory tank. I still have my factory tank, as a matter of fact, in case I just can’t deal with the overfill anymore. The whole point of this tank was not to have to deal with Jerry Cans and the leaking and gas on your hands that come with them!
Quite a lot. My charcoal vent line is a nice big loop. It didn’t overfill on the very first fill when I installed it but it has overfilled on every subsequent fill. How did you route your charcoal vent line?
Quite a lot. My charcoal vent line is a nice big loop. It didn't overfill on the very first fill when I installed it but it has overfilled on every subsequent fill. How did you route your charcoal vent line?
i did a few things on mine, but what seemed to fix it was just making sure that huge vent line didnt have any kinks in it. needs to be a smooth bend, i was only able to do that with the bed off. Now, i did also weld in an extra top bung that i hooked up a hose to thats currently blocked off if that other breather didnt fix the issue. I was going to have a second breather vent just incase, but havent needed it yet.
No kinks in mine. It’s a giant smooth loop up under my flatbed (and up around the full neck when I had a factory bed). I’m going to put my long vent tube in today and fill up to see if it clicks the pump off early and reliably.
The new, longer vent tube in the tank reduced the overfilling a lot! I’m relocating my filler neck sot hats it’s easier to fill with my flatbed. That bit of extra length in the full neck may be enough to end my fuel filling woes. Or I can make an even longer vent tube. It’s almost at its maximum length to be able to get it into the tank under the flatbed. I won’t make any more changes until I move my full neck. I’m excited to see positive changes though.
That’s exactly the point. The part my tank came with is way too short to stop the pump before it overfills. By making it longer, it shuts the pump off earlier...which stops overfilling. The key is to make it just the right length to fill all the way up but not overfill. That’s what I’m doing. I’m tuning it in to fill well on these high flow pumps every station seems to have.
Relocated the fuel filler today. With my flatbed, it was in a terrible location.
The two benefits of this are: 1. I can leave the pump in the fill neck like a normal car without having to hold it in the whole time. That sucks when putting in 30+ gallons! 2. The extra several inches of fill tube length along with my lengthened internal vent tube has almost eliminated my overfill problem! The longer internal vent tube reduced the amount of overfill A TON. But the added filler neck length just about finished it off. I’m going to see if I can fit in a longer internal vent tube to get this problem solved for good. When I filled up today, it spit the tiniest amount of fuel. I was SO HAPPY! It’s almost like having the stock tank again. I think I can get there with a bit more length on the internal vent tube. I may have to lift the bed up to get the tube in there then drop it back down but that’s not too hard to do.