Fuel caps

[Tom_Barb]

We were required to replace our 150 gallon fuel tank due to a crack resulting from the tank flexing as the pressure in the tank varying, as the fuel is used the space of that fuel must be replaced by air. the new fuel tank caps require a vacuum pressure to be created prior to the cap to allow any air to enter.
This is mandated by EPA so as to not allow fuel vapors to escape to the atmosphere.
As it turns out this pressure is too great for the large tanks, and will cause the tank to flex way too much.

be aware buy the proper caps.

[path1]

I've got one of these (link below) laying in my carport right now. You can have it if it will fit your fuel filler hose size, I'm near SeaTac. Best results the nipple gets a chunk of hose, then a pre 1970 VW bug fuel filter to keep out dirt, which is better than OEM, which is a nipple sticking out on top of fuel module.

Awhile ago on the Cummins web site, a guy spent lots of $$$ for a venting problem. Turned out his "vented" fuel cap was no longer venting because of dust/dirt in fuel cap mechanism.

http://cppdiesel.com/fass-rm1001-return-line-t-universal/

If your going to drill any holes, get a "stant" brand locking fuel cap. The type that has a cover tab for the keyway. Drill out the keyway slot that is under the tab and all the way through other side. The tab works as cover for the newly drilled "vent".

[SidecarFlip]

jplante4 wrote:

Good non explaination answer but I'd use a smaller drill bit.

[Tom_Barb]

wa8yxm wrote:
You may need to shop a vintage parts store but try the big suppliers like Witney (JC Witney) in Chicago or on line.. I mean you can still get Model T parts from them .

This is a great idea.

2 pounds pressure in a 150 gallon tank would be a working force of 14,768 pounds. With 2 HQ of Vacuum, the same is applied in reverse. work this tank that much over 18 years and you've got a problem.

[wa8yxm]

You may need to shop a vintage parts store but try the big suppliers like Witney (JC Witney) in Chicago or on line.. I mean you can still get Model T parts from them .

[K_Charles]

The vented cap should only be 2 PSI and 2" of vacuum.
The non vented cap is the one you don't want.
You can still buy them both.

[jplante4]

[Tom_Barb]

path1 wrote:
Subscribed...Sounds like they are making you upgrade to current standards. My 2001 Cummins 5.9 came stock with a vent on top of tank. I don't see why you would have to "upgrade" to a newer standard with the fuel system built by OEM in 2000.

All you can buy now are the pressure vented caps?

[path1]

Subscribed...Sounds like they are making you upgrade to current standards. My 2001 Cummins 5.9 came stock with a vent on top of tank. I don't see why you would have to "upgrade" to a newer standard with the fuel system built by OEM in 2000.