Fuel pressure drop after ignition
01-01-2018, 02:57 PM
#1
Member
Thread Starter
Fuel pressure drop after ignition
Hi everyone,
I have a 2011 E63 with the M156 6.2. I'm posting here cause I figured there are way more C63 owners with the same engine. I'm working on self diagnosing a crank issue on my car that searching the entire internet seems to leave me with no result, and just stories of people who could not resolve it. This should be interesting!
long crank problem - Page 2 is the original post - https://mbworld.org/forums/w212-amg/...ml#post7347124
Here is the specific issue I need your help with:
The fuel pressure in my car, when I put the keyless in position 2 (ignition) - shoots up to the normal range 60+ PSI (Measured via OBDII) and then comes down very quickly .. not to zero, but to the 20's. This is causing a long crank, and the car feeling breathless upon start, but the car drives totally normal and no CEL. Fuel pressure seems to be fine while driving - I keep my OBDII on and the pressure maintains 52-60 while driving.
The car also starts up fine if I crank the second time (Always first after sitting for an hour or two that is long, second or any subsequent starts are perfect). also starts up fine if I turn to position 2 about two times before cranking. (seems to build up more pressure)
The question is have is related to how our fuel system maintains pressure? is it via regulator? (I think the answer is no). How can I diagnose the root cause of the pressure drop?
Other people in this forum that have had this issue had their dealers replace so many parts with no resolution..
Thanks!
I have a 2011 E63 with the M156 6.2. I'm posting here cause I figured there are way more C63 owners with the same engine. I'm working on self diagnosing a crank issue on my car that searching the entire internet seems to leave me with no result, and just stories of people who could not resolve it. This should be interesting!
long crank problem - Page 2 is the original post - https://mbworld.org/forums/w212-amg/...ml#post7347124
Here is the specific issue I need your help with:
The fuel pressure in my car, when I put the keyless in position 2 (ignition) - shoots up to the normal range 60+ PSI (Measured via OBDII) and then comes down very quickly .. not to zero, but to the 20's. This is causing a long crank, and the car feeling breathless upon start, but the car drives totally normal and no CEL. Fuel pressure seems to be fine while driving - I keep my OBDII on and the pressure maintains 52-60 while driving.
The car also starts up fine if I crank the second time (Always first after sitting for an hour or two that is long, second or any subsequent starts are perfect). also starts up fine if I turn to position 2 about two times before cranking. (seems to build up more pressure)
The question is have is related to how our fuel system maintains pressure? is it via regulator? (I think the answer is no). How can I diagnose the root cause of the pressure drop?
Other people in this forum that have had this issue had their dealers replace so many parts with no resolution..
Thanks!
01-01-2018, 03:32 PM
#2
Member
Maybe check your oil for fuel dilution. I started having long crank issues when I had a fuel injector start having problems but not enough to cause a CEL until it was too late. If your injectors are leaking by then your oil may stink of gas. How long does it take for fuel pressure to drop off after having the key in position 2 without starting the car?
01-01-2018, 04:50 PM
#3
Member
Thread Starter
I checked the oil seems normal... it gradually loses 5 psi per second or so. So from 65 to about 20 in 5-6 seconds? This is all based off the OBDII.
wouldn't leaking fuel injectors have other symptoms?
wouldn't leaking fuel injectors have other symptoms?
