Mercedes trouble

Hi, I have a 1992 Mercedes 300SL convertable. I bought it last summer and it only has about 70,000 miles on it. It drove fine for a few months. Then once in the fall it started bogging down and stalled. Now, if it sits for awhile, it will start right up. Intermitantly it will bog down and stall, and then not start again until it sits for awhile. What is wrong with this thing??

It’s running out of fuel or running out of spark…Probably fuel. Change the fuel filter, check fuel pump pressure…

Like Caddyman I would suggest a likely problem with the fuel system and the steps he noted.

I would add checking for exhaust blockage to the list. This is easiest with a vacuum gauge.

Does this car have an over-voltage protection relay? These have been known to go bad and could cause these symptoms. I had it happen to my '89 Mercedes.

When it bogs down, what happens if you pump the gas pedal? If this kills it or does nothing, I’d bet on the fuel system. If you can keep it running by pumping the gas or giving it more gas, your electrical system may be shut down due to that OVP relay. This is just a guess though.

When I give it gas, it bogs down worse, or stalls. Thanks so much!

Mercedes trouble.

Isn’t that redundant?

Whatever Mac.

It would be great if your mechanic could hook up a fuel pressure gauge that you could monitor while driving. Fuel pressure probably drops too low for the injectors to work properly. Probably the fuel pump but I suppose a fuel pressure regulator could cause this too. Do you smell any gasoline more than usual (maybe in your garage after you drive it?)