Re: Gas odors

[Godfrey DiGiorgi <ramarren@domain.elided>]

Thanks for the note. I'm aware of the function of the check valves.

I'd noticed the fumes and the vacuum build up in the tank and been working
on it for some several months. I had cleaned, blown out, and replaced both
check valves three times. They continued to operate intermittently, no
matter what I did. Sometimes I'd get a big vacuum in the tank, sometimes I
wouldn't. The shop that does my Alfa service was trying everything they
could think of as well. All the lines were properly routed and hooked up
properly. There was nothing amiss with the rest of the evap recovery
system that we could discover.

The tank implosion occurred over a 50 mile stretch of road (about an
hour's driving time) when I went from Reno's 5000 foot elevation to 8800+
feet at Carson Pass, and back down to 4000' at Jackson. The tank was
oilcanned, the inner baffle was crunched, which necessitated the
replacement of the lifter pump, standpipe, sock, tank and fuel level
sender. Kind of an expensive lot of damage for a $.50 check valve!

Both valves had been replaced for the third time by then. It seemed pretty
obvious that the problem was the small plastic air inlet check valve.

I finally just removed the small plastic one and piped the 1/8" hose
under the car ... in the following 2000 miles, it never once built up a
vacuum in the tank and never again smelled of gasoline fumes. I can't
believe that a significant amount of vapor would be emitted by that small
a hose, particularly when the pressure differentials generally pull air
into the tank, not out through such a hose. 

I go with the solution that works. If others have had no problem with
these valves, that's fine. But everyone I've talked to who had gas fumes
in their car and removed the plastic check valve reported back to me that
they were finally rid of the gas fumes...

Godfrey

On Wed, 24 Mar 1999, Ferdinando Di Matteo wrote:

> Godfrey, the implosion  you had of the gas tank was caused by the plastic
> check valve being stuck shut and not allowing air to enter the tank as you
> burned gasoline.   The most simple solution would be for you to put in a new
> check valve which will not allow vapors to enter the atmosphere.  Every time
> you gassed up you got an inrush of air whenever you unscrewed the gas cap. 
> That was the tipoff for you to investigate and prevent the implosion. 
> Another check valve that occasionally sticks causes a pressure buildup which
> creates a very dangerous condition.   That's the metal check valve just
> abouve the plastic one.   Re-routing the hose is not a good idea.  Fred Di
> Matteo  USA AROC Tech. Advisor, Fort Myers, Florida

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