1984 380SL Starting problems - stumped

[Malc]

Hello
Our 380Sl has suddenly decided it doesn't want to start
I did eventually get it to start with a full throttle and a great deal of swearing so I could get it in the garage.
Now it refuses to start at all, well it actually sounds like its trying to start on three cylinders.... and the exhaust smells of petrol and the plugs are "wet" after several attempts.
However I read all the threads relating to idling problems and I am still a bit stumped as to what might be wrong.
I have
1.. Taken the idle air valve off - it works when checked on a battery.
2.. Cleaned all the connectors up to it
3.. checked the air mass meter plate is sitting correctly (it is)
4.. checked all the connectors to the temperature sensors - clean
5.. New distributor cap and rotor arm.
6.. checked all the plugs - fine
7.. I am getting spark to all plugs - checked with a timing light on each one
8.. looked for air leaks - none that I can find.
9.. Cold start injector operates.

Any help or suggestions would be greatly appreciated
Malc

 

[television]

Condensation on the rotor arm and dizzy cap are the number 1 suspects. The wet plugs indicate this is electrical. How fat is the spark ? firing under load is a very different thing to sparking in free air

 

[television]

You have not tried to adjust the screw in the throttle air flow plate have you ?

 

[Malc]

Thanks for the replies
Distributor cap and rotor arm are bone dry - plus are new Bosch items, not pattern parts.

Spark is a good size

Is the idle air valve supposed to be open (let air through it) when starting from cold or shut?

 

[television]

I will check on that this evening

 

[roofless]

un-plug the cold start injector it might not be cutting off

 

[television]

Re the aux air valve, off the car put it in hot water and it should close at 70c

 

[Malc]

Thanks Roofless I will give that a try again.
I did take the cold start injector out to make sure it was spraying properly, which it seemed to do with no drips or dribbles, it also stopped after a second or so - I assume this is correct operation

and Malcolm no I haven't touched any adjustment screws!

 

[roofless]

Thanks Roofless I will give that a try again.
I did take the cold start injector out to make sure it was spraying properly, which it seemed to do with no drips or dribbles, it also stopped after a second or so - I assume this is correct operation

and Malcolm no I haven't touched any adjustment screws!

that seems ok

 

[television]

I do have the test details of the components,,I will see if I can post a list of checking things

 

[Malc]

Update - Car now starts and runs:

It would appear that it was 2 problems at once

The first was the wires to the air bypass valve were corroded internally, especially where they join onto the "plug". I was getting the volts but not the required amps to work the valve. I had to cut the wires back about 3 inches before I found good clean wire. Soldered new wire and connectors in place, the valve now works rather well!

The 2nd possible problem was corrosion on the high tension output of the coil - not a place I would usually look! Took the lead off and the inside was black with corrosion and some form of debris .
Cleaned up, rubbish removed, lead contacts all cleaned up as well.
Guess it would probably be better if the coil was mounted horizontally or upside down to stop water or damp getting in.

Thanks to everybody for the help and suggestions while trying to deal with this problem
Malc