Original fuel tank go/no-go?

[erachner]

I'm in the midst of building 818S kit #38, probably one of the oldest unbuilt 818 kits out there. It has the original F5 fuel tank design, from before it was reshaped to make more legroom for the driver. I've read the forum threads about the difficulties with this tank related to leaks and venting, and I hope some experienced builders are still around to offer perspective on whether it can be made to work well at all - I haven't contacted Boyd to see if they still build their custom tank, and though it looks very nice, I think I'd rather economize and build a good car with what I've already got, if possible.

To address the leaks, I've taken the advice of this thread (https://thefactoryfiveforum.com/showthread.php?48739-Old-Fuel-Tank-Issues&highlight=B90229) and will be using nitrile B90229 o-rings instead of the F5-provided square rings. When I apply the ring clamps, the plan is to lay down a thin film of Hylomar blue on the tank surface and wet the rings with gasoline before torquing.

I'm less confident in my plan to address the filling difficulties that result from the fill neck port being situated relatively low in the tank. My understanding is it slows fueling since the fuel has to drain from the neck, and easy venting is critical to speed that along. I've got the factory charcoal canister, and my questions are:

1. Does the factory charcoal canister (from an '06/'07 WRX) have a rollover valve built-in, or should I source one separately and place that inline between the tank and canister?

2. Where the heck is a good spot to mount the factory canister? It's huge.

3. Will the charcoal canister still allow the tank to exhale freely during filling?

I'm open to using alternate charcoal canisters, provided I can meet the criteria of simple to assemble, rollover safe, easy exhale during filling, and no fuel vapor odors from the car.

Huge thanks for any advice y'all can offer. Cheers!

Eric

[Bicyclops]

Howdy Eric,

I've got the later stepped tank. In fact I've got an extra one here in SoCal if anyone is interested. I don't know how the early one went. Mine uses the Subaru oval pump and round sender plates. The rolled edges of the holes are pretty malleable. Easy to flex them and cause leakage when tightening. I used some sealant rated for fuel on the gaskets and just snugged the bolts. I addressed the low fuel filler directly by cutting it off and welding a plate over it. What a silly (stupid) idea to put it halfway down the tank! I made a doghouse to go on the top and cut up the filler pipe to make it mate up. The key to getting the tank to fill, in my opinion, is putting in the top of the tank, not halfway down. Mine fills reasonably quickly. I don't hook the pump nozzle on the fastest setting and as long as I'm paying attention, it doesn't burp out.


I just have a 1/4" tube from the fuel sender plate plumbed through the firewall for venting. At first I ran it to a rollover valve up high in the hump but smelled fuel every time I filled up. I extended the vent hose as high as I could get it and looped it down to dump under the frame. I don't have any canisters or fancy stuff like that. I still smell alcohol (E-85) sometimes when I'm flinging it around corners in the canyons but it's not annoying. I doesn't stink up the garage even when I fill up on the way home.

A rollover valve is just a gravity operated check valve. I don't think the WRX had one. If you do put one in, make sure it's in a vertical position or it will block the vent.

My nephew bought the Boyd tank and it's nice. It does hold less fuel than the FFR tank and it's aluminum which isn't the best if you're planning for E-85. With his ~10 gallons of gas and my 14g of alcohol, we'll probably have about the same range. With any wide skinny tank, there's likely to be fuel starvation in turns. Some folks are using Holley HydraMat. Don't know it that's a full cure. I went with a swirl pot behind the firewall and a lift pump in the tank to keep it filled.

Ed

[FFRWRX]

I'm open to using alternate charcoal canisters, provided I can meet the criteria of simple to assemble, rollover safe, easy exhale during filling, and no fuel vapor odors from the car.



I bought one of these (not for a F5 car). Supposed to be very good at eliminating odours, a decent size, and can be mounted anywhere. I'm mounting mine on the frame under the car; as long as the vent line runs up above the tank level before going down to the unit, that is fine.

https://www.vaportrapper.com/?srsltid=AfmBOoq1hVxC1NcAFdbuc0MIKAhNnI-tpmPcgI7A_NxoQyv7cVveOv8D

Rick

[idf]

When I first built my 818 I used the original Factory Five fuel tank with the o rings mentioned above and solved the leak issue. I didn't have any significant issues with filling. I later installed a Boyd tank primarily to allow me to move the seat back (and I'm only 5'6''). The Boyd tank is great. No fuel starvation issues in street use. I ran a vent along the filler tube with no charcoal canister and have not noticed fuel odors. No rollover valve, but installing one would be easy.

[lpmagruder]

I'm using the early version f5 tank with the o-rings you mentioned. Fought leaks for a while before getting them, but it stays dry now.

The fuel pump assy in the early kits is pretty DIY looking, I've been wanting to get one of the Boyd tanks but haven't had a "real" problem yet to justify the purchase.

[J R Jones]

My tank is from a 2014 kit, third owner/builder. The chassis is going under my Dino body and my fuel fill cap is higher.
I was dissatisfied with filling to the bottom and the fuel sender measuring the bottom 25%. I relocated everything to the top and recalibrated the fuel level sender.
jim

Sorry I have photos but I have not been able to load them for a couple of months with an odd exception or two. Dave H made suggestions for my end, but nothing works. Wow, third time is the charm.

212415

212416

[erachner]

Thank you all for the helpful replies! J R Jones, I'm mightily impressed by the improvements you made to the tank - I might attempt those since I have access to some expert metal help. (I'm even more mightily impressed by the inspired choice to put a Dino body on an 818. Can't wait to see that.)

lpmagruder & idf, I'm encouraged to hear that you've had good experiences with the o-ring solution; I think I'm going to move forward with the original tank. (Although at 6'1" tall I'm likely to regret it later, though I'm also oddly comfortable with less leg room than most.)

Cheers,

Eric

[J R Jones]

Eric, Thanks. The body is stored for the winter, I have limited space. I am installing Acura V6 drive and subframe. The structure is 90% and I am fabricating lower control arms leading to the coil over mounts and the last frame tubes. This is a test to see if my photo load process works again.
jim
212435

Weee, it worked.

[lance corsi]

Note to Eric; J R has been surgically altered to fit into the Dino!