suddenly my 1989 560SL won't start -- weird problem

[sshanky]

Hey guys,

My 1989 R107 never misses a beat and starts every time on the first try. This morning, for the first time, I couldn't start the car at all, after multiple tries. I should note that I am in Arizona, and it was about 60 degrees, so I doubt it was temperature related.

The starter turns over perfectly and normally, and the engine fires to life with the usual growl, but immediately (less than one second) it stops. Almost like no fuel is reaching the engine. But each time I turn off the key and try again, it does the exact same thing -- a quick rumble of life and then instantly shuts off. It doesn't stutter or try to start, but rather does exactly the same thing as if I turned the key right off the instant it started running.

I am suspecting a fuel pump but really I am just guessing. I'm not sure how to diagnose a fuel pump, nor if that is even the problem.

Any ideas would be greatly appreciated.

Thanks!

[tecqboy]

Fuel pump relay is most likely the issue.

[RadioTek]

From what I understand, the later K-Jet fuel system has sensors to tell it when the car is running after being started. The CSV (cold start valve) gives an initial shot of fuel after the pump is first started off for a couple of seconds. Then the pump shut down until the sensors say that the engine is running.

If you get the initial charge of fuel, it seems like you are getting the first phase of the process done, but you lose it at the second phase. The usual culprit for fuel problems like this is the fuel pump relay, but it almost seems like you might be missing a signal to it that tells it to start up again and keep going.

You will need to check to make sure the pump is getting power, to make sure.

I'm a D-Jet victim, so this is only a wild guess. You might want to go through the fuse panel and check for corrosion. There is a known problem with the "stock" type fuses. They are made with aluminum contacts and link, and the holders are brass. With a little moisture, oxygen, and time, this can lead to dis-similar metals corrosion. The two fixes for this are a) to get brass fuses, and b) clean the existing ones. You remove one fuse at a time, buff with a heavy cloth (not abrasive), put a tiny film of contact grease on the ends, and replace.

Just a few guesses.
Scott