Rich mixture

[Stimorolgum]

Hey friends.



I think I've done everything but still running rich.


The car is a 230SL with a newly restored engine and injection pump by previous owner.

New ignition system ( sparkplugs, leads, coil, distributor)

New fuel injectors

Cecked the Cold Start Valve for leaks.

Checked Warm Running Device, no Air through filter when warm.

Done The Linkage Tour.


The engine runs great and starts immediately when cold and after 4 seconds cranking when warm.
Could it be due to the Starter Solenoid on the back of the Injection Pump?

I don't know what else to check 

Any help is greatly appreciated 



Cheers / Martin

European 230SL from 1965

[mda]

fuel mixture nob is on the back of the fuel injection pump. Do not try to turn the idle mixture screw at the back of the pump while the engine is running, it must be off

[Stimorolgum]

Thanks mda


Of course I have some follow up questions.


I've been turning on that screw. I thought it was to adjust idle rpm?

Would I have to take it to a garage to measure the mixture by the CO?

May this be the reason for longer cranking time when warm?


Thanks again 

[Andrew C]

Hi. When you turn the know at the back of the pump the engine MUST BE  OFF.  Sometimes there a little difficult to locate you'll need to push it in whilst turning it slowly, once it locates it will move in about a 1 mm. Turn it no more than 3 clicks at a time.  Right is Rich. Left is Lean. Pop the injector pump rod off and see if it speeds up considerable when you open the air side. if it does its to Rich.  Switch off the car and twist the knob 3 clicks.  Check again. When you find adding air does not speed up the engine it's on the border of lean. Now switch off the car and go 2 clicks to the left. Now the idle CO  should be around 3 % If you check on a meter.  I would put in New plugs  NGKBP5ES.  NOT 6.  Make sure your linkages are adjusted properly.  Especially check the one going from the pump to the cross shaft isn't to long and stopping the pump returning to the fully closed position.  I've set up dozens of these cars and never had one I couldn't get right.  I'm an X Mercedes trained mechanic. I worked on W113 when they were regularly in for tuning and maintenance.  If you still have problems send me an email.  wychwood1@gmail.com
Andrew.

[Andrew C]

If you get a 12V  CO meter you can take it with you and check the CO under driving conditions.  You'll need it to be between 2 and 4 %. Depending on how your driving. full throttle should be around 4 %. Checked in 3rd gear.  Then if you think you are brave enough you can adjust the rack position on the pump.  It's not difficult,  go no more than 2 clicks at a time. Right is Lean. You'll need to be patient as it always easy to locate the screw head. You'll need a 3mm screwdriver with a perfect tip. After you adjust it you'll need to push and turn the idle CO knob about 3 clicks Right which is Rich. Always with the Engine OFF. Making the Rack Leaner will also make the start up Leaner.  You'll need 3% for a nice warm up.  It's takes a few days to set up properly due to the  hot and cold settings. 

[Andrew C]

When it's on the border of lean.  It's 2 clicks to the Right.  My correction.  Sorry.

[Stimorolgum]

Hello Andrew and everyone else.

Thanks a lot for the explanation.

After I posted last time, I unscrewed the barometric compensator.
I reduced the shims from 1.3 mm to 0.8 mm.
The idle rpm was higher after that, so I turned it down with that screw on the injection pump.

I took the car to a garage to measure the CO.
First it was 4%, and then down to 2%, after a small adjustment on the intake/idle air screw.

The engine still needs 4 seconds cranking on hot starts, I guess that's just how they are.


Regards

/ Martin 

[ja17]

You need to check your starting aids. I believe your engine has a round 1 second relay.  Make sure it is working during hot starting.

[Stimorolgum]

Hello

Yes, my 230SL has that relay, I will definitely look into that.

There is a good explanation about the time switch on the Pagoda SL Group Technical Manual.

I also understand that the bimetallic thing inside the relay goes bad or needs adjustment, after many years.


Will try next week.


/M

[Stimorolgum]

Hello again

Now I have adjusted the Time Switch relay.
I took it down from two seconds to one second by turning the adjuster screw 45 degrees ccw.


The hot starts are now slightly better I believe.
The engine almost starts the first second due to the cold start valve, and then starts after one more second of cranking.

Over all, I am satisfied with the car. I've put many hours in to it and it runs and drives very well.

 

[Skippermitch]

I have an older 230sl 1964.  I was fouling plugs on a hot start.  I pulled the connector to the 1 second time switch and solved my over-rich start.