Mercedes fuel pumps

[Martin Easterbrook]

Mike,

I've done this type of thing in work with some Porsche 911 Turbo fuel
pumps as a cheap way to get 20bar fuel pressure for some fuel injector
tests.

I burst tested a pump first (in a safety cell) to check if it would be
safe.  The burst pressure was 35bar.

I know of several people running series electric pumps on race cars to
get high fuel pressure (= better fuel atomisation from the injectors)
but I have never heard of a setup like this on a road car, as most
road cars only run 2.5 to 3 bar anyway.

I could see a point in connecting them in parallel, particularly for a
high capacity engine that needed a lot of flow.

I think the failure you saw is most likely to have been caused by a
faulty regulator or a blockage in the regulator reflow line.

Martin



Mike Morrin <mikem at southern.co.nz> wrote:
>
> I was in at a local shop today, and they had a 1990 Merc 560SE (or
some
> such model) on the hoist, with fuel spewing out of one of the fuel
pumps
> (everything switched off).
> 
> The car has two standard looking Bosch pumps, but they are plumbed in
> series, so that the outlet of one pump goes to the inlet of the
other.  In
> this case the crimped join in the case of the second pump had
apparently
> burst.
> 
> The car had probably sat for a few weeks before the fault happened
(stuck
> pressure regulator?)
> 
> So why put two standard pumps in series?
> 
> Is the aluminium body of the pump really rated to take the outlet
pressure
> of the other pump?
> 
> Anyone else seen a failure like this?
> 
> regards,
> Mike
> 
> 
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