E320 95 Intermittent Start Problem

[duc4208]

I've recently experienced intermittent start problem on my 95 E320. In the last few days, the car sometimes does not start. Hot or cold start it does not matter. When it start, it run fine. My wife is scare now because after park a car few minutes, she could not start the car. After trying several start for about 10-15 minute, then it start again. I expect some thing wrong with relays. Last time, I experienced the intermittent problem with the turn signal. It turned out that the combination relays was faulty (has black burn mark in the I&C board inside the relay). I changed the combination relays and it work fine since then. Where should I begin? Any suggestion is greatly appreciated.

[Arthur Dalton]

Archieves "OVP relay"

[duc4208]

Originally Posted by Arthur Dalton

Archieves "OVP relay"

How do I take out the OVP relay. I saw a screw attach to it, but I has no room to remove unless I have to remove the battery. If the battery is removed, do I have to entet the security code for the radio/cassett/CD.

[Arthur Dalton]

Need code before bat disconnect.
Test the relay fuse first and next time you have the problem , tap the relay
If you do take it out , see if it is the old part #
You canget to it with hood at full up-right w/o bat removal
Archieves

[duc4208]

Thanks Arthur. I took the fuel pump and the OVP relays out after removing the battery. I have the code for the radio/cassett. I disassembled the fuel pump relay for visual inspection and it looks fine. Measured the coil resistance and it was about 600 ohm. I think the relay is o.k. About the OVP relay, it is the old part number. Ordered the new OVP today. Will install when it come. Reading the forum about the problem with OVP, I think that this may be the problem. I will pray. But if the problem comes back, I will buy a fuel pressure gauge to see if the fuel is delivered to the fuel rack with pressure. I will also use a timing light to see if I get a spark in one of the spark plug. Does the fuel pressure gauge in Advance Auto Part store fit the fuse rack testing plug? It is used in GM,Ford, and Chysler cars. Thanks a lot for your technical help, I did save a lot of money to fix the car myself in previous problems. I will keep you inform if the problem is fixed .

[Arthur Dalton]

I am not sure of that particlular pressure gauge set-up. The Benz test port uses the same fitting as the R12 a/c charge ports.
Any way you chose to check for either spark or power to injectors will indicate OVP , as OVP is power source for ECU , which controls both ign and fuel injectors , but not fuel pressure, That is FP relay, but you already seem to know that.
I think you will find upgrading the OVP will solve the problem
Good Luck

[duc4208]

Installed the uprated OVP with new part number. So far the car starts fine. Driving to doctor, cinema, and shopping, the car starts every time. I disassembled the OVP relay box and found some oxidization on the I/C board. I think the problem was I/C board. Beside saving money, I accomplished something which makes me feel very good myself. Special thank to Arthur Dalton. He knows these stuffs very well.