When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
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.
Today, 10:18 AM
