Re: [DML] Re:Fuel Cell Question.

[Martin Gutkowski <webmaster@xxxx>]

The "Euro spec" cars had several changes made to them to satisfy the 
over-zealous registration procedures at the time. Somebody decided that 
because no european car had a composite fuel tank at the time, they must 
be less safe than a metal one, so that was one of the required 
modifications. I don't think the fuel pump being mounted outside the 
tank was a safety concern as European cars of that time also had pumps 
within the tank. Perhaps it was purely easier to make the tank!

I have also had fuel tank woes caused by the original pickup hose. If 
you'll indulge me, I'll attempt a little physics lesson.....

There's no such thing as negative pressure. Or to put it another way, 
suction is not a force in its own right. The pump picks up fuel by 
lowering the pressure on the pickup side and atmospheric pressure forces 
the fuel up the hose. For this reason the "amount of suck" a pump has 
can never exceed atmospheric pressure - roughly 15psi at sea level. 
Mounting the pump on top of the tank will add about 6" to the height the 
fuel must rise - this more than doubles the pressure required to get the 
fuel out of the tank - or to put it another way, this more than doubles 
the work the pump must do in order to drop the pressure sufficiently on 
the intake side to get the fuel up the hose. I would imagine the design 
specs for the pump have this well in hand, so if it works without any 
complaints, I for one would not lose any sleep.

HOWEVER lowering the pressure in the suction hose even further increases 
the possibility of the suction hose collapsing. I have had headaches due 
to the original hose collapsing, but have noticed that the bore of that 
hose need not be anything like as large. My pickup is 1/4" bore and 
drawing through a nice little in-line filter with ports the same size 
(but a considerably larger element than the stock pickup filter). James 
RG has noticed how an apparently solid fuel line becomes soft and flabby 
and prone to collapsing as soon as traffic and a hot day combine to heat 
your fuel up enough. If you do move the pump outside the tank, make sure 
your pickup hose is suitably reinforced (mine's steel-braided line).

Martin
#1458


jamesrguk wrote:

> Hi all,
>
> I may be corrected here by one of the UK DeLorean buffs, but it is my 
> understanding that the European spec cars had metal fuel tanks with 
> the pump mounted on the top apparently for saftey reasons.
>
> The car on this page has the european setup.
>
> www.delorean.co.uk/pictures/dcp01652.jpg
>
>
> Regards
>
> James RG
> England