Diagnosis needed

[JamesL]

Dear Doctors

Got a little problem with my 280. When pulling away, the car stutters. The rev pick up is far far from smooth and indeed feels at times like it's being starved of fuel and will stall. Once above about 1200 revs, and moving, the car sounds great and picks up nicely. Until I get to about 4000 revs when it almost feels as if there's a rev limiter in place. Push it and it sounds like it's trying to backfire

I'm running a Cranes electronic ignition, and odly enough, the problem is worse when the engine is warm/hot than cold. Stopped and the car sounds fine. (in fact, since the Cranes went in, the car has revved better but has always felt a little sluggish from a standing start)

If I get a rolling start, the pick up is better but from a standing start, the old right foot seems to have the effect of making the car want to stall

Due for a service over the next week or so and so wanted your advice on where to start looking. My instinct tells me fuel or ignition.

Thanks, in advance

[Cees Klumper]

Sounds like ignition trouble to me (timing, wires, coil, resistor etc); although I would check all of the usual suspects like fuel delivery, air leaks etc.

Cees Klumper in Amsterdam
'69 white 280 SL automatic

[Benz Dr.]

Sounds more like fuel to me if it runs better when it's cold. This sounds like the fuel pump or plugged lines. ALWAYS do a fuel delivery test BEFORE you start wasting time looking for some other problem. If the car is missing that would more likely be ignition but this one will nose down when you give it some gas.
Blow through the fuel return line with the fuel filler cap off. You should hear bubbles in the fuel tank. If not the line inside the tank is plugged up. Car will run but not very well.
The fuel pump should easily deliver 1 liter in 15 seconds. If the fuel pump makes noises that change in tone it's on the way out.

Daniel G Caron