Fuel tank venting

[Clyde's Keeper]

At this time, I'm committed to using the FFR tank and have been reading about the many shortcomings including poor venting. I have the later style tank and am currently modifying the '06 fuel pump and level sensor. Part of this includes making a vent out of one of the tubes. I was wondering if enlarging the vent might help with the filling of the tank. Seems to me you could tap a larger fitting in the place where it will vent. Maybe a barbed fitting either tapped and well sealed into the plate or even with a lock nut on the inside and well sealed. Would effectively double the size of the vent.

Thoughts???

Thanks, Robert.

[fastzrex]

At this time, I'm committed to using the FFR tank and have been reading about the many shortcomings including poor venting. I have the later style tank and am currently modifying the '06 fuel pump and level sensor. Part of this includes making a vent out of one of the tubes. I was wondering if enlarging the vent might help with the filling of the tank. Seems to me you could tap a larger fitting in the place where it will vent. Maybe a barbed fitting either tapped and well sealed into the plate or even with a lock nut on the inside and well sealed. Would effectively double the size of the vent.

Thoughts???

Thanks, Robert.

The Boyd tank has its vent in the center and uses an AN fitting. You have a good idea for adding a vent for the original steel tank. Buy an AN bulkhead fitting (it is extra long and has two sets of threads) in a -4 or -6 size. Drill a hole for this fitting and use bulkhead fitting nuts on both sides with a copious amount of fuel resistant sealant. While there are many sources for these fittings, Summitt has a large selection.

[wirenut]

Does Boyd have an updated tank for the gen 2?

Does anyone with the new tank have the fuel starving issues?

[Hindsight]

Yes, the new fuel tank has starvation issues. Had to get a fuel surge tank to address them. Someone used holley hydramat with fairly good success... might be ok for the street but not the track.

When venting the tank, you need to consider two things: 1 - venting while filling it at the gas pump, 2 - venting for expansion and displacement.

For #1, you need a large vent tube that goes from the top of the tank to the top of the filler-neck, but is covered by the gas gap when the gas cap is closed. Should use 1/2" ID hose minimum for this. Requires welding and modification of the filler neck.

For #2, I did basically what fastrex stated, but did so on the new FFR tank, not the boyd tank. With the new FFR tank, you can use one of the three pump-top barbs as a vent, but if you do, you have no rollover or slosh protection. Even though I had my vent line going up to the top of the frame and then back down, I still spilled lots of fuel going around corners, and again, no rollover protection. So ultimately, I capped it off, got a fuel discriminator value from FuelSafe (it allows venting in and out, but doesn't allow fuel to go out, and also acts as a rollover valve), drilled a hole for it in the top of the tank right next to the fuel pump, and installed it with it's hex nut. Since it is bulk-head fitting and comes with a fuel-safe o-ring to seal it, there is no need for thread sealant. I've had no leaks. The discriminator valve had a -6 or -8 AN fitting... forget which. I just got an adapter from that to a 3/8" hose barb and connected some fuel hose to it, up to my home made charcoal cannister.

I have pics of all this in my build thread.

[phil1734]

You can buy an in-line check valve that doesn't require any special tools or modifications to install.

https://www.pegasusautoracing.com/productdetails.asp?RecID=899

I've had mixed results with them. It seems to me that they work well with sudden rushes of fuel such as a rollover or autocross, but a gentle ramp up to maximum Gs they tend to not shut properly. I put one at the end of my vent line that is run up to the front center of the engine cover and haven't had any problems yet.

[Hindsight]

Phil, I had one of those initially as well. Got it from Pegasus too. But it just allowed too much slosh for my liking which is I replaced it with a discriminator valve.

[STiPWRD]

Does Boyd have an updated tank for the gen 2?

Does anyone with the new tank have the fuel starving issues?
The Boyd tank will fit behind either gen 1 or 2 firewall.
http://www.fueltankparts.com/factory-five-818-10-gallon-gas-tank-with-aeromotive-stealth-340-pump.html

[wirenut]

The Boyd tank will fit behind either gen 1 or 2 firewall.
http://www.fueltankparts.com/factory-five-818-10-gallon-gas-tank-with-aeromotive-stealth-340-pump.html

Well that makes my decison much easier....