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D2 - Fuel and Exhausts Everything to do with getting fuel into the engine, and fumes back out again

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Old 9th December 2018, 11:06 PM
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Conan_the_Librarian Conan_the_Librarian is offline
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Default Fuel pump teaser!

So, what's this all about?
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Old 14th October 2020, 11:05 AM
RB1 RB1 is offline
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I know this is an old post, but I tried this MAGNETI MARELLI 313011300066 pump recently. It has the small output in the bottom to pressurize the venturi system, but I never got it to work unless I topped up the fuel level high enough to fill the collector, lets say, naturally by fuel level.

Then, I went to start the S8 in the garage, and now it is completely dead. Its not seized (like the one that came out), but even when wired direct to the pump, it does not run. It is behaving like an open circuit.

Has anyone else fitted this Marelli Pump and had problems, either with normal fitting/operation or reliability?

Richard
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Old 14th October 2020, 01:05 PM
MikkiJayne MikkiJayne is offline
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We never fitted the Marelli pump to a car - its sitting in a box in my workshop.

Your fuel level problem sounds like the standard pump houing location issue tbh, but the pump dieing like that is sub-optimal.
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Old 15th October 2020, 07:06 AM
RB1 RB1 is offline
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Quote:
Originally Posted by MikkiJayne View Post
We never fitted the Marelli pump to a car - its sitting in a box in my workshop.

Your fuel level problem sounds like the standard pump houing location issue tbh, but the pump dieing like that is sub-optimal.
Thanks. I suspected the same, and used a Borescope camera to make sure it was seated correctly where the output pressure for the Venturi sits into the cup/funnel. the important "D" shape gasket at the bottom is in good condition also. Is there something else to watch out for?

I guess I am unlucky with the pump, but now I probably will not order another Marelli, I may just go for the VDO pump.

cheers
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Old 15th October 2020, 11:33 AM
MikkiJayne MikkiJayne is offline
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The hose for the return line needs to be tucked in to the pump bowl. I've seen the same problem when its been reassembled with that line loose outside the bowl.

Its not unheard of for the pump to be assembled correctly and everything to look right but it still doesn't work. There's legend of a mystery pipe inside the tank which can come adrift and also cause the problem. People have swapped the complete fuel tank to solve it.

Its plausible that the Marelli pump has the stub but not the internal gubbins to push fuel through it. If it was reverse-engineered from the VDO unit the point of that outlet might have been missed and its simply a moulding artefact. Having not tested it myself I couldn't say whether it actually works as expected.

The VDO pump is not really that expensive in the scheme of things.
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