Goni C63

Hello everyone I have a question about fuel pump! I test the fuel pump pressure and once I turn the key ON fuel pressure shows 70psi once I start the car goes down to 60psi once I keep RPM's at 3-4K PSI drops to 49-51 PSI I got the fuel pump already but don't wanna install it yet if it's going to be something else since I can't return it once I install it and these are the cods I have P228f code p0101 p010b p420 p430, would like to hear your input.

Thank you!

HYPERTUNE

I'm not familiar with the fuel system in the C63 but in most systems it's entirely normal for fuel pressure to drop when you start the car (some cars do run constant pressure systems though...). The pressure regulator maintains a constant pressure relative to the intake manifold so when you have a vacuum in the manifold (engine running at idle for example) the fuel pressure drops accordingly.

If however the pressure is dropping as much as you say (70-49= 21psi) that would indicate the fuel pump is faulty as fuel pressure is dropping by more than one atmosphere.

QWKSNKE

Are you checking it with the car stationary or going down the road?
I assume you are checking on the fuel injector rail, is at the the end of the rail? ( I have never looked)

To be fair, 50 psi of fuel pressure is still a lot.
Is the pressure regulator on these cars electric or vacuum operated

QWKSNKE

Do any of those codes represent low fuel pressure?
Sorry, I don't have a code dictionary handy

Edit... Just read where the fuel pressure is controlled by a module that varies the voltage to the pumps to make the pressure go up and down based on demand

mthis

did u try changing the tune and see if the codes come.again?

roadtalontsi

to add to this .... Actually 2 separate fuel pump control modules, one for each pump. they are pulse width modulated - do not apply direct voltage to them it may cause problem. There is still a regulator but it's located in the passenger side fuel sending unit. 4.5bar is typical mb fuel pressure spec. It is normal for it to peak high and drop slightly after startup, this helps with fuel vapor lock.

What are the code definitions?

avery.whss

if you have a tune, thats why..alotta you guys run your tune all year round..BAD idea, you all need a winter tune..every year within the same week my car acts weird as hell and feels like it'll blow up anytime, i switch the tune to my winter tune and runs fine..its because the AFR is all whack this time of year

if your fuel pumps are shot you'd barely be able to drive the car, it'll shake, rattle, barely idle. I've been through 2 sets of fuel pumps and it's the same every time