I had one check valve seal okay, and one soft. I learned the hard way that you need to remove the plastic hose from the valve by gently heating it before attempting to remove it, or you'll break off the nipple.  You'll want to remove the tanks to inspect them and replace the seals, and my tanks were glued in with undercoating.  

Stuart

-----Original Message-----
From: Neil N [mailto:musomuso@gmail.com] 
Sent: Wednesday, March 05, 2014 9:41 AM
To: Stuart MacMillan
Cc: vanagon@gerry.vanagon.com
Subject: Re: Was: Residual Fuel Pressure... Now: Dirt PIC

Hi Stuart. Very good point. A check valve seal may be at fault.

As you know, it's hidden up there in the wheel well, with all the dirt.    ;)
All other seals, hoses etc. are in good shape as I resealed the tank not that long ago.

NOT saying this is the same part, but the VC tank has a similar or same marking on it as the tank I installed: http://tinyurl.com/mbw2nmc My amateur skills aside, (aligning the large type filler neck is a small pita), the filler neck hole in my tank didn't exactly line up with the hole in frame which, in part, caused a leak at the filler pipe to tank grommet. Images:

before filler neck re-align
http://tinyurl.com/lxvqzp3
after
http://tinyurl.com/mu7ll6h
not a great shot, but kind of shows poor tank to frame hole alignment http://tinyurl.com/l2ngelr

I replaced that grommet and re-aligned the filler pipe parts. It hasn't leaked since.

Really appreciate the suggestion of check valve seals. I wondered of the evap system but that may be the weak link.

Neil.

On 3/5/14, Stuart MacMillan <stuartmacm@gmail.com> wrote:

>..... check the two vent tanks in the
> wheel wells.  The check valve seal can soften and fail, and the tanks 
>can  crack.

> .... Frankly, given all the junk in your tank, for the price of
> $175 I'd replace it:
> http://www.van-cafe.com/home/van/page_1178_1457/fuel-gas-tank.html

--
Neil n

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