Fuel Pump no pressure when priming, not holding pressure when off
06-18-2016, 04:14 PM
#1
Fuel Pump no pressure when priming, not holding pressure when off
2006 C230 M272 100,000 KM
For the last two weeks the car has been really hard to start, it will crank and sputter and eventually fire and run normally. It happens mostly when it has been sitting for a few minutes to an hour. It happens about 75% of the time.
I hooked up a fuel pressure tester.
Video of the fuel pressure.
I swapped out the fuel pump relay and it made no difference.
I shorted out the fuel pump relay to be always on, I get 53psi all the time. The car starts in a heartbeat, no stutter no delay.
For the last two weeks the car has been really hard to start, it will crank and sputter and eventually fire and run normally. It happens mostly when it has been sitting for a few minutes to an hour. It happens about 75% of the time.
I hooked up a fuel pressure tester.
- With the key ON (but engine off) I get a slight pump in pressure to ~10psi then immediately back to zero.
- Turn the key to start the engine the fuel pressure jerks and stutters up slowly with the engines sputters, finally when the engine starts I get 53psi (normal range)
- Once running the car drives normally, zero issues.
- When the engine turns off it immediately looses all pressure.
Video of the fuel pressure.
I swapped out the fuel pump relay and it made no difference.
I shorted out the fuel pump relay to be always on, I get 53psi all the time. The car starts in a heartbeat, no stutter no delay.
- I blocked the fuel return line where it returns to the tank under the back seat behind the driver.
- Key on. engine off, pressure jumps to 100psi (max for the meter)
- engine starts, 100psi
- engine off, it holds pressure at 100psi, and it slowly bleeds pressure 1-2psi every 5-10 seconds.
11-22-2018, 01:10 AM
#3
Junior Member
I have a 2013 c63 coupe p31 pack and ive recently been having similar problems, wasnt sure if it was due to running e85 constantly via advanced dynamic fuels e85 kit or it was jus due too premature failure of many c63s but when i first removed the kit the car seemed fine but before the car read different codes and had hiccups especially in M mode when i had spirited drives... long story short i re installed the kit as i felt the car was much slower on 91 octane and boy am i regretting it... the same symptoms of jerking came back except only this timea different code came up as p228f for fuel pressure regulator as "too much pressure" which is different then other having " too low pressure"...its very embarrassing when your in a nice c63 coupe or sedan and your car takes off like **** infront of everyone watching(these cars break necks every corner).
