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I am experiencing fuel pressure issues with my 2006 W221 S550 (M273 Engine).
At the Fuel Rail when measuring the pressure it goes up to 12+ BAR, and this is my 4th fuel pump as my guess is they keep burning out due to high fuel pressure.
I have this style Fuel Filter in my car and when I took off the cover I noticed that there are no wires plugged in in to the sensor and it acts like just a Plug, I also was not able to find any electrical connectors that should plug in to this thing apart from the main plug.
Could someone let me know if there should be a plug connected to this sensor for the S-Class, or its an issue with the fuel regulator which is attached at the bottom of this filter?
the red circled bit in your picture is a fuel pressure regulator - with that design the pump runs (when triggered to do so - aka all the time when its started) and makes too much pressure - this blows the regulator valve off its seat, thus bleeding away excess pressure to whatever the spring feels like producing today
obviously its designed so pump pressure being enough, pushes fuel through the white plastic body - which is a clean top secret fuel filter (they pretend you don't have) - and the regulator outlet diameter and the spring make the rail pressure the manu wants
too much pressure is interesting - are u fitting the correct spec pump ? or is there a muddle up on pipework ? some brands just squirt out back in the fuel tank - others do a detour for some reason
The fuel pump is correct, operating pressure on fuel pump says its 3-4 BAR. No blockage in the lines.
Is this pressure sensor being used in the S-Class? Like I am not able to find electrical plug for this sensor and this sensor just acts like a plug for a hole
a mechanical regulator controls the pressure
all the wires we need is to run the pump
if you wanted to measure the pressure to inform the engine management whats really going on - you'd do it at the rail under the bonnet not at the back of the car where its fairly irrelevant - but then its a merc and Germans never understood engineering....
a mechanical regulator controls the pressure
all the wires we need is to run the pump
if you wanted to measure the pressure to inform the engine management whats really going on - you'd do it at the rail under the bonnet not at the back of the car where its fairly irrelevant - but then its a merc and Germans never understood engineering....
Reading the WIS information it states that Fuel Control Unit should use this sensor to control fuel pressure, there are no sensors under the hood or on the fuel rail itself apart from 2 mechanical fuel pressure regulators.
PWM controls the pump voltage then... so why have a mechanical pressure regulator - all rather strange, surely it would thus need to be set very high?
wonder where your wires went ?
That's the thing, on WIS when searching by VIN it shows a different style fuel filter for this car which doesn't have the Fuel Pressure Sensor (Most likely this is a facelift fuel filter):
But for sure this is not the correct fuel filter for my car as I have bought it from the dealer and the fuel ports don't match up in size with fuel lines.
I have ordered the correct fuel filter with the regulator from MB dealer which was 220 euros... will arrive on Tuesday, but now I am wondering if the issue is that this plug is missing or if its that regulator
sounds like it - probably needed for the later engine with direct petrol injection.....
if u have access to WIS you can look up parts in EPC then ?
Looking at EPC it shows this fuel pressure sensor in the diagram, but there are 3 different part numbers for the fuel filter itself:
I don't know if I still need to dig to find that plug for the sensor or if its just a faulty regulator, as if I install that new Filter on Tuesday with the new regulator and it doesn't help then its 220 euros down the drain (I guess the filter will be new atleast )
I can see a direct injection car 278 would need a far high fuel pressure and likely would need to vary the pressure based on combustion pressures (aka high load)
whereas a 273 is a basic thing where anything dribbling out of the injector will be enough
then we get to the drawings and the descriptions...
is part 55 a sensor ? or really the mechanical fuel pressure regulator - the assembly of an early 273 engine's "fuel pump" likely breaks down to a eleccy pump, a mechanical regulator and the filter - and a new regulator would likely be a needed part
the filter might changes, but is this just a parts housing change during builds or really a capability change / different set up for other markets etc.?
I don't get the wording..... from low vin number and too a higher Vin number sounds back to front to me....
I can see a direct injection car 278 would need a far high fuel pressure and likely would need to vary the pressure based on combustion pressures (aka high load)
whereas a 273 is a basic thing where anything dribbling out of the injector will be enough
then we get to the drawings and the descriptions...
is part 55 a sensor ? or really the mechanical fuel pressure regulator - the assembly of an early 273 engine's "fuel pump" likely breaks down to a eleccy pump, a mechanical regulator and the filter - and a new regulator would likely be a needed part
the filter might changes, but is this just a parts housing change during builds or really a capability change / different set up for other markets etc.?
I don't get the wording..... from low vin number and too a higher Vin number sounds back to front to me....
Well this is confusing for me also, first time for some reason when I checked EPC and entered the VIN it didn't register it fully (only hadWDD221171 entered instead of full the VIN).
Ok so now when I check EPC with full VIN entered it throws me a fuel filter with this part number A1714700690:
Here is a picture of this Fuel Filter:
I have bought this Filter from MB Dealer yesterday, as they searched for this part by my VIN and it didn't match the fuel filter that I currently have.
Fuel Filter Part Number which is installed in my car is A2214701390 which is this:
As you can see the first fuel filter doesn't actually have a sensor (which by VIN should be installed in my car), also the fittings on this filter are different for attaching fuel lines.
The one that is currently installed does have a fuel pressure sensor at the top.
I know that my car was rear ended in the past as the paint work on the rear bumper is not great, what I am wondering is that the Fuel tank may have been damaged and it was replaced from a different year model hence why I don't have any wiring for this Pressure Sensor.
Part 55 states that its a Pressure Sensor to Pump.
I hope that this makes sense my brain is no longer functioning tbh after full day looking at parts/diagrams.
post above post makes sense - except clarity on connectors....
I would think the early car didn't get an electronic pressure sensor and only builds 5 bar and regulates down to 4
I can image the 12 bar u see is the wrong pump for your car (and as you say these had an electrical pressure sensor)
if it had a crash that warranted a fuel tank - I'd have thought you'd need a whole car not a fuel tank.... so we end up back on connectors - seems highly plausible to me the person fitting the wrong pump also swapped you to the wrong (matching) connectors
post above post makes sense - except clarity on connectors....
I would think the early car didn't get an electronic pressure sensor and only builds 5 bar and regulates down to 4
I can image the 12 bar u see is the wrong pump for your car (and as you say these had an electrical pressure sensor)
if it had a crash that warranted a fuel tank - I'd have thought you'd need a whole car not a fuel tank.... so we end up back on connectors - seems highly plausible to me the person fitting the wrong pump also swapped you to the wrong (matching) connectors
Specs show that operating pressure is 3-4 Bars, I guess I will just install the new fuel filter which matches my current by code and will go from there, maybe that fuel regulator at the bottom of the filter will solve this issue.
Changed the Fuel Filter, with a new fuel pump from a different brand, the issue stays the same it goes over 3-4 BARs to approx 10-12, to be honest not sure what to check next.
I thought - though went round the houses twice, and contradicted yourself a bit - you have the wrong later pump and need the older simpler set up...
as early M 273 cars get something like a 5 bar pump and regulate mechanically down to 3 to 4 bar
and M 278s get a high pressure pump to suit direct injection with a different pump that is electronically controlled (I guess based on when engine management calls for it)
The fuel pump part number that I keep installing is A2214705994 / A2214701694, which is specifically for the M273 engine so I doubt that it is wrong, this time I even bought it from a different manufacturer and the issue stays the same.
JohnLane, there are 2 fuel pressure regulators on the Fuel Rail but I doubt that they are at fault:
u r still confusing me.... the way I have read most of these post is: '
you got the car with a pump with an extra electrical socket (with nothing connected to it) and that pump burnt out - three more of the same type also keep burning out
during investigation (after 3 failures) you find the car is getting >12 bar fuel pressure - when the docs you have shows its meant to get 4 bar
you then found this extra connector (you don't have a wire for) on the pump present in your car is meant to be part of an electronic fuel pressure regulator
then you started to believe its possible the car has the wrong pump and dealers parts dept want stupid money for the other type so hadn't yet tried one
after some back and forth posts with me, you found videos of cars with the connector wired up - and then documentation from merc saying its an electronic pressure regulator on later cars '
you went back and had further discussions with a dealer about what pump you need - and they say you need the other type, but its costly
I also proposed it needs the simple one, you then looked but struggled to find conclusive evidence on parts docs, then after another attempt found it needs the simple pump the dealer has been telling you this chassis number needs - but are reluctant to buy it
and last intended to give the wrong later pump yet another go (and now this weekend you report this one is also doing the same 12 bar pressure)
u r still confusing me.... the way I have read most of these post is: '
you got the car with a pump with an extra electrical socket (with nothing connected to it) and that pump burnt out - three more of the same type also keep burning out
during investigation (after 3 failures) you find the car is getting >12 bar fuel pressure - when the docs you have shows its meant to get 4 bar
you then found this extra connector (you don't have a wire for) on the pump present in your car is meant to be part of an electronic fuel pressure regulator
then you started to believe its possible the car has the wrong pump and dealers parts dept want stupid money for the other type so hadn't yet tried one
after some back and forth posts with me, you found videos of cars with the connector wired up - and then documentation from merc saying its an electronic pressure regulator on later cars '
you went back and had further discussions with a dealer about what pump you need - and they say you need the other type, but its costly
I also proposed it needs the simple one, you then looked but struggled to find conclusive evidence on parts docs, then after another attempt found it needs the simple pump the dealer has been telling you this chassis number needs - but are reluctant to buy it
and last intended to give the wrong later pump yet another go (and now this weekend you report this one is also doing the same 12 bar pressure)
? am I muddled....
The pump is not the issue, the pictures that I sent previously are Fuel Filters and not the Fuel Pumps.
W221 M273 facelift and pre-facelift use the same Fuel Pump but different Fuel Filters (not sure why merc changed the part between facelift and pre-facelift ).
The thing is that EPC and MB Dealer states that my car should have a different Fuel Filter which doesn't have that sensor at the top of the Fuel Filter, but Fuel Lines in the fuel tank that connect to the filter are different between the facelift fuel filter and pre-facelift and you can't install another type fuel filter.
So that's why I was guessing previously that the fuel tank must have been changed from Pre-facelift to Facelift type hence why I have a Fuel Filter which has the sensor at the top but no wiring on the car. Unless I am missing something obvious here .
until this year I had no idea about these in tank units....
now it seems the car and motorbike industry moved to these "hidden" jokes for cheap assembly at point of manu - on a 20 year old toyota I've been driving and it turns out on my BMW bike the white thing is really
a fuel pump
a fuel filter
a fuel pressure regulator
and where the gauge sender unit clips on
on a toyota its all stripable and individually replaceable... and why the "bit of plastic" is so costly when buying everything as one unit
until this year I had no idea about these in tank units....
now it seems the car and motorbike industry moved to these "hidden" jokes for cheap assembly at point of manu - on a 20 year old toyota I've been driving and it turns out on my BMW bike the white thing is really
a fuel pump
a fuel filter
a fuel pressure regulator
and where the gauge sender unit clips on
on a toyota its all stripable and individually replaceable... and why the "bit of plastic" is so costly when buying everything as one unit
Well Mercedes thought of a different design for some reason , on one side of the tank there is a fuel pump which just has 2 simple wires going in to it, on the other side this "Fuel Filter" stands which has that fuel regulator and on Facelift that pressure sensor.
Fuel tank from scrapyard costs 400+ Euros in my country so I guess this will be my next expense and a project on replacing it and resolving this issue..
part of my post went missing - my bike has a right to left transfer pump (that is non electric), and a real injector pressure electric pump on the left - I can imagine on the W221 to get fuel from the wrong side of the tank - with the propshaft in the way - to the side that gets it to the engine, we need a pump both sides...
maybe I'm an idiot, but I believed I've read people always playing on the left side with the "fuel pump" and if not, why would we have a mechanical pressure regulator in the wrong place
early S550 / Europe S500
left side (but isn't this really the main fuel pump too ?)
050 FUEL FILTER UNIT FUEL TANK 001 A 17 147 006 90 - $83.99
050 FUEL FILTER UNIT FUEL TANK Replaced by: A 221 470 17 90 001 A 22 147 013 90 - $126.55
050 FUEL FILTER UNIT FUEL TANK 001 A 22 147 017 90 - $133.42
055 PRESSURE SENSOR TO PUMP Replaced by: A 000 905 11 00 001 A 00 354 275 18 - $49.54
055 PRESSURE SENSOR TO PUMP 001 A 00 090 511 00 - $69.47
right side
080 FUEL PUMP FUEL TANK Replaced by: A 221 470 84 94 001 A 22 147 059 94 - $320.02
080 FUEL PUMP FUEL TANK 001 A 22 147 084 94 - $456.69
080 FUEL PUMP FUEL TANK 001 A 22 147 060 94 - $398.68
080 DELIVERY UNIT FUEL TANK 001 A 22 147 074 94 - $398.68
The fuel pump part number that I keep installing is A2214705994 / A2214701694, which is specifically for the M273 engine so I doubt that it is wrong, this time I even bought it from a different manufacturer and the issue stays the same.
JohnLane, there are 2 fuel pressure regulators on the Fuel Rail but I doubt that they are at fault:
Fuel supply to rail only on your photo. No fuel return line. Those guys on the fuel rail are pulsation dampeners.
It will likely use pulse width modulation to vary fuel pressure.
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, on one side of the tank there is a fuel pump which just has 2 simple wires going in to it, on the other side this "Fuel Filter" stands which has that fuel regulator and on Facelift that pressure sensor.
