Car running rich

[glcg123]

My 1965 230SL 4 speed is running rich. There is some black smoke coming out the exhaust car when I accelerate (it does not use oil). Also, the tailpipes are black on the inside, not a grey brown colour.

I have read that there are two adjustments on the fuel pump - a high speed adjustment, single screw behind a capscrew, and a mid-range adjustment, two black screws behind a plate that you remove. This plate has the low speed idle adjustment thumbscrew. The car starts well in all conditions and pulls hard.

Has anyone had success with these adjustments?

George

[Ulf]

Don't have any answers for you, by my 230 SL displays similar sympthoms, so I'll keep my eye on this thread to see what comes out of it. Tried a fresh air filter? Plugs?

Best regards

Ulf

[ja17]

Hello glcg 123,

Good advice from Ulf, try the cheap and easy items first. What is the history of the problem. Did it occure all at once or has it been a gradual issue?  Make sure the linkage is correct. A slight linkage mal adjustment can cause this kind of problem.  Do a split linkage test to see if the engine is running rich at all speed ranges or at specific rpms.

Removal of an oval shim under the WRD or from under the altituide compensator will change the mixture at all speed ranges.  Adjustment of the rack screw will also do the same.  The oval shim removal is easiest to try and put back if needed. If you are not familiar with these fixes let us know.

Make sure everything is correct before diving into the complex and expensive injection system!

[glcg123]

It has a new air cleaner filter. I did not change the plugs as they have been the light brown colour. I have owned the car for 5 years and average 1500 miles per year. It was carboned up and I have run it hard to clean it out. However, it seems to be coming back.

I am taking it out of winter storage in the next 2 weeks and will let you know how I made out.

Than you for your suggestions.

George

[Ulf]

It seems like my car mostly displays the same symptoms when only driven for short trips as it doesn't have the time to get sufficiently warm, but after at brisk 40 mile drive, it really purrs. Have heard that these cars are prone to contaminating the oil with unburned fuel especially when being driven for short distances only and that this can cause carbon build-ups.
So maybe you should just take it for a nice long drive! Not a bad thing to do, huh?

Best regards

Ulf