W113 Pagoda SL Group > Drive train, fuel, suspension, steering & brakes

Idle Screws Adjustments

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Skitzerow:
My car has a strong rich gas smell when started cold.

I would like to know how the idle screw on the injector pump and idle air mixture screw on the intake on a 1968 280sl is adjusted.

How can the starting point for adjustment be made.

My car has a strong rich gas smell when started cold.

SDK

rwmastel:
SDK,
You may not be in need of an adjustment.  You may simply have a leaky fuel injector or cold start injector which leaks fuel after the car is stopped.  This would allow extra fuel to be there when the car is started, causing your fuel smell.  You may also have a leaky fuel line, but I hope not! [:0]

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420

hands_aus:
hey SDK

Use the SEARCH function and look for "linkage". There has been many discussions about the fuel injection pump adjustment and idle air screw adjustment.

Also have a look in the Technical Articles.

Is the smell of fuel in the engine bay or the exhaust gas?

Bob (Brisbane,Australia)
early 250 SL, RHD

Skitzerow:
The gas smell comes out of the exhaust....Thanks

quote:Originally posted by hands_aus

hey SDK

Use the SEARCH function and look for "linkage". There has been many discussions about the fuel injection pump adjustment and idle air screw adjustment.

Also have a look in the Technical Articles.

Is the smell of fuel in the engine bay or the exhaust gas?

Bob (Brisbane,Australia)
early 250 SL, RHD


SDK

George Davis:
SDK,
The idle settings should only be adjusted after everything else is working correctly, including ignition system.  If the idle mixture is set too rich, the car will idle rich when it's warmed up.  Suspect other things first, like a leaking CSV or injector as mentioned by Rodd.  There may be other possibilities if these aren't the problem.

The CSV should have a small 7 or 8 mm hex screw in the side.  If so, you can check for CSV leakage by removing this screw, then put a rag below it and drape another rag over the CSV to catch fuel in case it leaks a lot.  Turn on the ignition so the fuel pump runs, then check the screw hole.  If fuel is dripping, dribbling, spraying out, the CSV is leaking.  The factory spec is no more than 3 drops in 60 seconds.  New CSVs are expensive, but many owners have successfully repaired them themselves for next to nothing.

Fuel injectors are probably best checked off the car with proper test equipment, which I understand is rare, but a diesel or injector shop can get close.  I imagine there are DIY ways to check leakage on the car as well, if you're so inclined.

Good luck!



George Davis
'69 280 SL Euro manual

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