380sl 1981 - don't start when warm

[blueshield11]

I have bought recently a 380sl 1981.
The problem is starting. At first it started right up. But some days ago I wanted to start the car (cold) and it did not start. After numerous tries finally I got it started. Let it run for a while and I noticed that in the beginning it ran with 1000rpm and after a while it went up to 2000rpm.
I thought it would be normal the other way around.
After that I turned off the engine and tried starting, but no way.
After a long time and several tries it started. I let it run for some time and when I put down the gaspedal a bit the engine shut off.

On this car I cannot find a adjustment screw for adjusting the idle (like I had on my former 380sl from 1983).

- Is there a difference between 1983 and 1981 concerning the idle adjusting ?
- Could this be a vacuum problem ?
- could it be the idle speed control unit ? if so , how can I check this ?

I would appreciate any help on this one.
Thank you.

[ja17]

Hello,

Check for any vacuum leaks in old rubber hoses on the intake manifold first of all some of them are buried. Next the idle on later SLs like yours is controled by an electonic idle control valve. Sometimes these need cleaned. Look for an electircal plug and hoses on a round solenoid like device (front top of engine). Warm up regulators get stuck and cause problems also. Make sure the fuel filter is clean before you start checking expensive electricals!

[tonytiger]

Where is black lick,Ohio? Do you know Joe the plumber? I agree with your assement totaly. If you get the vacuum lines routed correctly and fix leaky ones that goes a long with proper running car.

[blueshield11]

thank you very much for the input.
I have checked the vacuum hoses on the intake manifold and I have discovered that 1 was not connected right. So put it back on and problem was solved.