nostra23

Hi all,
I got a 350CGI and a kind of strange issue. I miss a little bit of power and have high fuel consumption.
ODB error shows P0148. My high pressure pump made really loud ticking noise and the E350 CGI 2010 has already like 140k miles on it.
I then measured the rail pressure and it is 200 bar in idle. When I go for normal drive it goes from 190-200bars. However, if I push the pedal it drops to about 140 bar.

I though this is a clear issue and I have to change the high pressure fuel pumpe. 3000$ later I changed the pump on my own.
I am not sure if the issue is gone. I have the feeling that there is a little more power but rail pressure still drops from 200 bar in idle to 155-160 bars with full throttle.
The fuel pressure from the (normal) fuel pump shows 4.6bar - no matter how much I push the pedal.

I am not sure if I resolved my problem with the new high pressure pump. So two questions:
What is the fuel pressure from the normal fuel pump - is 4.6 bar fine?
What is the range of the high pressure fuel pumpe? Is it ok with full acceleration that pressure drops from 200 to 150 bar?
Any other ideas?

Thanks so much!

JettaRed

iTrader: (1)

Were those $3000 USD?

Please provide your VIN or at least full model number.

CaliBenzDriver

Two good pumps and still a fuel fault...


-- Is this a STORED or CURRENT code?

-- Using what sort of OBD scanner ??

-- It would sound like the tank pump is starving your new HPFP but your test shows low pressure is feeding well.


++++ Rail sensor...???

S-Prihadi

Nostra wrote, in blue :
01. I have the feeling that there is a little more power but rail pressure still drops from 200 bar in idle to 155-160 bars with full throttle.
That is normal, at high load and RPM fuel pressure is reduced to that 150ish BAR.





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02. The fuel pressure from the (normal) fuel pump shows 4.6bar - no matter how much I push the pedal.
That is too low, you want to see 5 BAR as minimum.
The High Press fuel pump minimum pressure input from Low Press fuel pump is to be at 4 BAR.
From fuel filter where the LP fuel sensor is giving you that 4.6 BAR, its piping to the engine and all added resistance in flow, you loose approx 1 BAR.
So when you see 4.6 BAR at that in-tank fuel filter LP pressure sensor, the High Press fuel pump get only 3.6 BAR.

140K miles and I assume you never ever replaced the fuel filter...yes ?
That is a big mistake already.



Here is dirt in fuel calculator I made, you multiply it by 400% for your case, because your car has burned 20,000 liters at least.
Even having super clean fuel at 0.001% of contamination or 10 PPM, the amount of dirt in that small fuel filter is already PLENTY.




So first to do is : replace your fuel filter which you need it anyway, and then test again.
To see a fixed 4.6 BAR at all times, there is a possibility your fuel filter fuel press sensor is sticky-stuck ( not only very dirty ), it should swing.

Here is a 35,000KM fuel filter vs new one


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See the RPM of each gear pull.



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Have fun replacing the in-tank fuel filter. When you replace it, please drain it to a container to inspect the fuel dirty-ness at the CLEAN OUTPUT side and show us.
Read here : https://mbworld.org/forums/e-class-w...el-filter.html



Prepare fire extinguisher close by when doing fuel filter.
Also the RIGHT side tank ( where the LP fuel pump is at ) will always have more fuel than the LEFT side tank where the fuel filter is.
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nostra23

Oh my. S-Prihadi - thank you so so so much for this data. This is exactly what I was looking for. I tried also to look this up in WIS but couldnt find it.
So two findings then: The first HPFP was defective (the noise was so loud... it sounded like it just wants to jump out and it fell below 140 bar) - but not the cause of the problem.
I got the car only some weeks and there was a note that fuel filter was serviced but I didnt check it tbh. I thought the 4.6 bar staying constant means that the pressure is fine.
I would have expected that the pressure drops if there is an issue - like HPFP is sucking more fuel than pump can deliver.

Anyway, S-Prihadi I am very thankful for your post.

On the other questions: it was a current code, it was a standard ODB scanner (no xentry/wis) - but this one works very well for standard odb data, Were this 3000$ (dont understand the question)

Thanks!

S-Prihadi

To test Low Press fuel filter pressure sensor is easy, but you need a decent scanner or a Xentry. OBD2 gauge can not read the LP fuel data.
Minimum get a Launch MB specific or better its bigger brother to do all cars.
Best is to get BenzNinja Xentry, where you will get his lifetime support. https://benzninja.com/

If baby Launch, MB only. Gen 1

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baby launch , MB only, Gen 2

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baby launch, MB + BMW + Audi.


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All brands: Wired & Wireless
if wireless :

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To test LP fuel pressure sensor value.
Scanner ready reading N118 fuel computer, to read low pressure side fuel system.
Bleed the fuel carefully at its schrader valve ( at engine LP fuel test port ) and see the LP fuel pressuer value dropping to about 1 BAR minimum low because of the remaining fuel in the pipe.
Can't be zero, unless your disconnect the blue plastic fuel hose at fuel filter, which can be dangerous is battery is not disconnected and scanner can't read N118 fuel computer without battery connected for the car.



Read post #11 : https://mbworld.org/forums/e-class-w...ml#post8621982

Follow up post : https://mbworld.org/forums/e-class-w...re-sensor.html

The two post above will show you what N118 fuel computer can show for its data and what can go wrong with the High Press Fuel + Temperature sensoir.


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If you want to replace your Low Pressure in-tank fuel filter, read here : https://mbworld.org/forums/e-class-w...er-change.html


1 big question : Dealer will charge you US$3,000 for your HP fuel pump replacement or that is the cost for you to do DIY ?

nostra23

Here in good old Germany the pump costs 2700 Euros, so around 3000 USD. There is no way to import the (US produced pump) cheaper... unfortunately.
Mercedes charges for an original pump directly from the dealer 5200 Euros... so the 2700 from the import guy is already a bargain

So this is what the "well taken care of all maintenance done" filter looks like... will post after I changed...

JettaRed

iTrader: (1)

Did you pay US$3000 for a new HPFP? What cost US$3000?

nostra23

why is this important for the problem resolution?
THE PUMP ITSELF is 3000$.

JettaRed

iTrader: (1)

That's CRAZY!!! The HPFP in the US is 1/10th that price.

JettaRed

iTrader: (1)

It's not. It's just shocking.

JettaRed

iTrader: (1)

Have you contacted FCP Euro? They ship internationally.

nostra23

Guys, I appreciate your efforts but I already have my pump. If you buy from Mercedes its even worse:


s

S-Prihadi

Aha, I see, that HP pump of yours belong to the rare GDI of M272 engine.
https://www.ebay.co.uk/itm/385117981975



Yes, this kind of pump is NOT CHEAP due to low volume sales.
The M271.8 EVO is also using similar pump design and I heard it is expensive too, albeit no more than 120-150 BAR if I am not mistaken.
This one uses camshaft azz end to spin the HP fuel pump, not like our newer GDI with low cost small sized Bosch HD5 family of pump using fuel lobes pushing the plunger Up-Down.

JettaRed

iTrader: (1)

YIKES!!!! That might even total a car.

nostra23

S-Prihadi. Is the table/value you shared around low pressure and high pressure fuel pump also valid for this setup? Thanks!

S-Prihadi

I can't confirm that, as I never log M272 GDI version, never even seen one before, only read about it.

I would not worry about HP pressure being reduced to 150 BAR on your set up at certain RPM or load. 150 BAR is more than enough to atomize the fuel.
The ECM will play with the injector opening duration to get the proper amount of fuel.

If you have access to Xentry, you can see the list of DTC and sometimes the DTC parameters/explanation are clear enough to learn from it,
perhaps the minimum pressure of HP fuel pump triggering the DTC is there.

nostra23

ok. talking about low pressure pump. that should be same as shared. lets see whats happening with new filter

S-Prihadi

See your LP fuel pump, how many wires into the pump MOTOR itself ?
If only 2, that means your pump is not the 3 phase pump, still older pump type. if 3 wires, that is 3 phase fuel pump.

nostra23

Three i guess

S-Prihadi

There is a float wire there too in your photo, I meant is you must lift up the green cover and see the motor.
If the connector as per photo only has 3 wires, you are not using 3 phase fuel pump.
3 phase fuel pump will have up to 6 wires. 3 big wires for motor,1 big wire for ground and 2 small wires for fuel level float.

my 3 phase fuel pump



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