Have Mercedes Questions? Ask a Mechanic for Answers ASAP
Hi Nick, I need to know how you are testing the pressure. Can you send me a picture of your pressure gauge set up?
Hi Nick, I need to see how the gauge is connected to the car.
Hi Nick, if you are just checking the pump output pressure at the rear you will have 145 psi. To check the system pressure you will need to perform the test at the fuel distributor.
What is the history of the problem? Will the car run on ether?
Hi Nick, the first thing I would do is a fuel mixture adjustment. If the mixture is adjusted too lean it could cause the hard starting problem. The cold start valve only helps the starting and it only sprays for a second or two. If the car takes longer than that to start and if it runs poorly until it warms up I doubt that the valve is the problem. Fuel pressure is probably ok since you have good pump pressure. I'd start with a mixture adjustment and see if it helps. Cold starting is controlled by the EHA valve located on the side of the fuel distributor. You need to make sure there is power to the valve or you won't have any cold enrichment. Power comes from the CIS control unit and the control unit is powered by the overvoltage protection relay. I think you will find that your problem is with the mixture and the EHA control.
To disconnect the alarm just remove the glove box and unplug the two plugs on the alarm control unit. It has nothing to do with the starting problem.
Let me know if you have any questions.