Hello: I've exhausted myself reading threads on this issue. My 1990 300SE with the M103 engine would not start this afternoon. Over the last week I had noticed it was taking a little longer to start than usual. Well, usual for this particular engine was nearly an immediate start. After reading many threads from those who had similar issues, I've come to believe there is a problem with either the fuel pump, fuel filter or fuel pump relay in this vehicle.

I poured some gas directly into it and it started. I had someone turn the ignition on and off and heard no sound coming from the fuel pump and I was lying on the floor right under it.

So, what is the most likely culprit and how do I find out for sure which one it is? I have read about "jumping" the fuel pump relay. I don't know where that relay is nor how to jump it.

If you post a suggestion please do so in the simplest terms. I can certainly follow directions, but I need all of the steps in order to do so. I'm just learning these cars. Well, I'm just learning cars in general.

Thank you.