Gas tank fitting / insert?

[DangerNewb]

Anybody familiar with one of these? It's installed in the top of a plastic fuel tank in a recently purchased boat. It leaks some fuel. The center has arrows for open and close but I'm not able to get it to spin. The flap that folds up to turn it seems to be plastic so I've not put too much pressure on it. Not sure if its leaking around the outer ring or the threaded in center piece. Thinking I can take the nuts off the outer ring and see if I can get the entire piece out and reseal with permatex. Either way I'd like to fix it. Any advice is appreciated.

[FUJIMO]

[David - WI]

https://www.speedwaymotors.com/Speed...SABEgKT7PD_BwE

1/4 turn... one review says it got so hard to open he had to wreck it, but the replacement was fine.

[FUJIMO]

...it states that the red cap is vented.

[DangerNewb]

...it states that the red cap is vented.

In the reviews Q and A they say the cap is vented one way. In. Not out. Seems they offer new seals also. May check into those. Not sure why it was ever installed in a boat tank. It has the normal fill and vent spouts in top of tank.

Guess I'll try to get the insert out. Remove the flange and reseal it. If not, a new tank may be in order. Seems fitted for the boat. Stv procomp.

[CI STV]

That’s a standard race car fuel cell filler cap assembly. All you need to do to get it open is flip the little T-shaped lock up, rotate it as far as it can go CCW, then yank hard on it to pull the lid off. They tend to stick easily once they corrode and can be a bitch to get loose. The little button is the vent, but your tank should be properly vented otherwise, so you shouldn’t need that. That looks like the whole assembly should be replaced, including the gasket. If it leaks gas fumes out, that’s a fire hazard and chances are it will leak water in too.
Here’s what I use to replace those cheap plastic pop-off lids. It’s anodized aluminum with a screw on lid assembly and it comes with the gasket and hardware. The lid has an O-ring seal. It’s not vented, so you need to make sure that the tank itself is vented.
https://www.jegs.com/i/JEGS/555/153590/10002/-1

[FUJIMO]

...spray a small amount of penetrating oil on the red cap so the o-ring will break loose. like CRC or simular. only other place it could be leaking is the mounting gasket. also, you can make up a glass of soapy water in a glass & pour a small amount on the entire fill & then slightly pressurize through the vent hose while a friend studies where the bubbles emit from at the fuel fill. only takes 3 pounds of air pressure to accomplish.

[FUJIMO]

...yeah, it probably should be replaced with a more "marine" oriented fill design. looks like every time you undo that cap, water/dirt falls into the tank. hard to tell from the photo though.

[DangerNewb]

...yeah, it probably should be replaced with a more "marine" oriented fill design. looks like every time you undo that cap, water/dirt falls into the take. hard to tell from the photo though.

I'll spray some PB blaster on the screw cap and see if I can get it loose. The tank has separate fill and vent lines so this is completely unneeded for my purpose. If I can get it sealed up I dont care if it ever opens again. Thanks for all the input.

[Chaz]

Somebody got their moneys worth out of that one , it don't owe ya anything . Jeg's also sells those caps and base rings that you have there ..
Love the billet one though .. More than likely they buy them from "The Chassis Shop" in Mears Mi. since it's a spittin image of the caps and bungs they make in house ..
When filling any tank like that , the fill cap ring should be grounded . Personally I've not seen a static electrical spark when filling a tank , but I'm not lookin forward to the first time either …

[CI STV]

Yep, those “tapered seat” flush-mounted fuel cell caps are fine when they’re in the trunk of a race car, but they don’t fare well in a marine environment. The Jegs screw-on billet cap appears to be identical to the Earl’s/Holley version, albeit about $10 cheaper. It’s also waaay prettier than the regular cap and comes with stainless bolts too. I installed one on the intercooler ice-water tank on my car (yep, because the damn tapered seat cap kept sticking) and I just use a small amount of anti seize on the threads. But for a boat, I would just use some two-stroke oil to lube the threads every time I refuel.
I’m just about to start rigging my STV Mod VP, and I’m certain I’m going to replace the cap that comes on the fuel cell with one of these as well.
I will definitely remember to put a ground wire on it now too!

[H2OPERF]

The one i used is like the jegs works great.I made a 2 pc threaded aluminum plate to screw into instead of the nuts on the inside.

[CI STV]

That’s the same one I bought, except in black. Pretty smart idea to do the threaded backing plates, since holding each nut with a wrench while tightening the bolts is a bit of a PITA.

[FUJIMO]

...when boat builders/manufacturers build a new boat, it's part of coast guard regulation, and b.i.a. (boating industry association) regulation, to ground the deck fill to the fuel tank for prevention of static build. when filling a boat with fuel at the gas dock or gas station, etc., the high rate of fuel flow going down the inside of the rubber fuel fill hose, creates the static. new boat builders do this a few different ways. the cheaper builders just strip off a bunch of wire insulation off a length of 14 gauge green ground wire at the top end, and bend it over the top and into, the new fill hose, and then push the hose & clamps onto the bottom of the deck fuel fill fitting. some rivet the wire to the fill. some a ring terminal & attach to one of the mounting machine screws. every builder does it their way. the tank end of the aluminum tank fill hose ground wire is done all different ways as well.

[H2OPERF]

Funny i just took one apart with the stripped wire laying over the inside of the hose method, never seen it done that way before and I thought it was kinda crappy so i put it back with a terminal under a thru bolts/nut and grounded it at a fuel sender mount screw.