Thanks, Mark

   I figured it was some kind of plumbing loop...like you describe...I
shall proceed to re-assemble, let the van down level again and give her a
go...I didn't see any grime or grit from any of the filters and I didn't
actually run the pump backwards...My pump is about 40k miles old
now...might be getting worn out but I put it back on for now....I have the
original as a spare the one I changed out a few years ago in a pre-emptive
maintenance move so till I get a new one I'll cross my fingers with this
noisy one...or maybe clearing the screen in the tank was it....

On Mon, Mar 24, 2014 at 5:16 PM, mark drillock <mdrillock@cox.net> wrote:

> It depends on how full the tank is. The outlet pipe is in the shape of an
> arch inside the tank over to the center bottom pickup point. Once you clear
> the fuel out by back flowing air it can only fill the arch and drain out by
> gravity if the fuel level inside the tank is higher than the high point of
> the arch. Once the arch is filled with fuel it will then be able to drain
> the tank all the way due to the siphon effect.
>
> Mark
>
>
> Don Hanson wrote:
>
>>
>>    Here's the question:  When I took the supply  line from the tank to the
>> pump off before I put the compressed air (50psi) backwards into the fuel
>> tank, the gas flow out of the disconnected hose was very
>> free-flowing....and now I get barely a dribble out when I unplug that
>> hose...When I put the air into the  hose, I took the gas cap off and I
>> could hear the air going into the tank...lots of bubbling noises...   I'm
>> thinking I should see a free flow again from the hose that goes to the
>> pump, the outlet from the gas tank....but it is only a little
>> trickle....Is
>> that the way it's supposed to be?  Should I see a strong flow out of the
>> unpluged line to the pump from the tank?  The gas cap is still off, the
>> van
>> is raised a bit on the passenger side, there is appx 1/3 tank of fuel
>> aboard...
>>
>>    What say the fuel tank experts.?
>>
>>