85 380sl starting problem
 

I have a 85 380sl. I couldn't get the car started. The engine will start for 3 sec and die.. I changed out the rotor, cap, wire, plugs, and check the coil and looks good. any idea? I can't find the fuel pump relay..
any help?
thanks

The fuel pump relay is on the right side of the passenger footwell. You remove the under-dash covering to get to it. It is the largest relay, and is black.

I still couldn't find it.. there are a couple of black relay in there. do you have a picture or a part number for it? thanks

Sorry, I'm travelling and don't have any documentation with me. It's the tall one.

Try Fastlane on this site - I think they have a picture.

Got another question.
If I turn the ignition key to on, should the fuel be on?
I hook up a meter to the fuel pump, no voltage to the pump. It got the voltage when I crank the engine.. is this normal?

The pump should run when you first turn the key on, then stop. It should also run when the engine is cranking or running. I don't think it runs with the key on/engine off because it is designed to shut off if there is an accident and the engine stops but the key stays on.

Probably a bad relay or maybe no RPM signal to the relay.

I placed a jumper in the relay. pin 7, 8 to bypass the relay.
the car still stalled after 3-4 sec after it start..
I am running out of idea.

Well you did good, you proved the relay wasn't the problem. You still must decide whether there is enough fuel pressure.

About the only way to do this without gauges is to remove an easy injector with the fuel line attached and bypass the relay as you have. First view that NO fuel should flow from the injector with the motor not spinning.

Next, place a finger on the airflow meter and push down. Fuel should flow in proportion to how far you push. If not you have found a problem.

If there is fuel flow you still must verify that the mixture is acceptable. Crank the car and once running (you did say it ran for a couple seconds) press gently down on the airflow meter. Try and add fuel as the car dies. Try to find a spot where the mixture is best by moving your finger gently, smothly, slowly up and down. This of course only works if your are too lean to start with.

Verify that the frequency valve is buzzing when the car is cranked and during the brief running.

The problem is I am working on the car alone. I figure let me change out the fuel filter first.. I don't think that had been changed for a long while. I have ask a friend of mine to help me out later. thanks for all your help. will keep you up to date