[W126 Coupe] running on empty (was Rims)

[Sharan Bains]

There were two options for fuel tanks with the w126, short range and long 
range tanks. Your SE may have the short range tank.

Just looking at the set-up and location of the fuel tank and fuel pump 
should explain why I think there is no validity in the 'always run with a 
1/4 tank' philosophy.

The fuel pump and associated filter/accumulator is all lower than the bottom 
of the fuel tank with respect to height. So even if the tank only has 1 
litre of fuel, the fuel pump will be submerged in fuel as it sits lower than 
the the bottom of the fuel tank. The fuel line running to the fuel pump runs 
from the base/bottom line of the fuel tank, not at any higher level. So the 
fuel tank would need to be bone dry for the pump to run dry.

The fuel pump will only run dry once your tank is dry...at which point the 
car wil stall to a halt and you'll switch the engine off. So your pump will 
not run dry for long. The fel only cools the pump - the fuel has no other 
function. The pumps will not seize up if run dry even for a good 5 minutes.

So whether the fuel tank is full, 1/4 or 1 litre, pump is submerged in fuel 
whilst there is any amount of fuel in the tank. Hence the level of the fuel 
in the tank is irrelevant. At least on the w126/w124/w201 models.


talbir


>From: "Shayegan, Richard" <rishayegan at davidson.edu>
>Reply-To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>
>To: "Mercedes Coupes Mailing Lists" <mbcoupes at mbcoupes.com>
>Subject: RE: [W126 Coupe] running on empty (was Rims)
>Date: Fri, 9 Sep 2005 08:17:59 -0400
>
>-----Original Message-----
>From: mbcoupes-bounces at mbcoupes.com
>[mailto:mbcoupes-bounces at mbcoupes.com] On Behalf Of Sharan Bains
>
> >What manual suggests running above 1/4 tank at all times ???? That's
> >complete trash IMO.
>
>Actually, the manual for my dads '98 5-series says to, and the mechanic
>who replaced the fuel pump on nobody's (nobody wants to be associated
>with it) '94 Oldsmobile said the same thing, though that's a different
>story because on that car the fuel pump is inside the tank.  But I was
>more thinking that I had read one of the authorities on here say that
>it's bad to run low on these cars.
>As a side question, do the SEC's have bigger tanks than the SE's? My
>tank only holds about 85 liters.
>Richard
>The MB Coupes Website!
>W126 SEC Mailing List
>Postings remain property of MB Coupes, L.L.C.