Hi forumers,

I'm from Malaysia and Had the car since 2013 and has been good all this while. Was rear ended and after the bodywork, car couldn't start so dealer jump started and replaced the battery. Car also misfired once in heavy acceleration.

After all this the car would start when cold and after driving it for a short distance (i.e. Fill in petrol) then when I go and restart it the car would not start and when it did it will start then die after a

The star diagnostic mentioned fuel pressure low. So a fuel pump was changed and it also asked for the ecu to be replaced. Both were replaced but car still start could I check?

 

Hello, This sounds like a grounding issue. All cars, electrical fuel pumps, normally have a
plug in to the wiring harness and the wiring harness has to have a attachment point from the harness to the body. 2 possibilities to look at first, Did the repair facility clean the electrical plug by the tank and use dielectric grease ? Second is usually , on the main negative cable from the battery to the engine is a grounding bolt bolted to the body . Where I live in Canada this is a ongoing issue.due to deicing compound on our winter roads. The cure is unbolt it, clean it and use dielectric grease , then re tighten, After that your car should have a fuel pressure test port somewhere on the fuel rail. It should be a Schraeder valve. You can temporarily put a test gauge on and watch what the fuel pressure from the pump is. This will show a weak pump, pinched line.< Possibility> or wrong pressure. Just because you have a new pump installed, does not mean it is delivering correctly. It may not have been a faulty pump giving the star low pressure. A plugged filter quite effectively does thatas well. Allan

 

Hi
Sorry for the late reply.. They diagnosed the engine harness as faulty. Changed that and car was ok then now it will die in the morning once after the first start stop operation? They are now stumped as to what is causing this. I am also at a dead end.

 

Hello, I am not familiar with your particular car. However I am certain that your mechanics have dealt with similar issues in automobiles other than Mercedes. A lot of manufacturers use a collision switch, or several. This is to prevent your electric fuel pump to continue pumping after a collision Further some manufacturers incorporate a minimum oil pressure signal as a roll over shut down.
Your mechanic needs to find and check / reset the collision switch. If that is not the problem , then they must listen to the fuel pump while the car is started. When the engine starts it should continue to run. If not its time to look at a wiring diagram to diagnose the problem. Good luck Allan