idle adjustment screw

[maxevans]

I'm an owner of a 69 280sl and am having problems with getting the fuel adjustment correct. I have read alot about the adjustment of the linkage and the such and still can't get the fuel to lean out enough. I know they say turning the idle adjustment screw on the injection pump counterclockwise leans the mixture out but is this from the front of the car or from the rear of the car since I have tried both ways to no avail. Any suggestions?

[Jonny B]

Counter clockwise as if you were able to look at the adjustment screw from the rear of the injection pump (toward the front of the car).

[Cees Klumper]

Like Jonny says - plus, the only way to turn the screw is with your right hand approaching it from the firewall-side; and then the direction is counter-clockwise.

If leaning it out that way is insufficient (and you've ensured that the intake flap is close to binding when idling), then removing a shim from underneath the barometric pressure compensator - the round 'canister'/'hatbox'-like widget that sits on top of the FI pump- could do the trick. Removing shims has the effect of leaning out the mixture across the entire range (idle, mid and full-load range). Our FI pumps tend to wear rich, so this may work for you.

[maxevans]

Thanks for the info on the direction of the screw. I have turned this a few times in the correct direction but it still seems to be running rich. I have gone through the linkage tour  enough to get the fi pump and the intake flap on their stops with the flap closed. I have also set the linkage rod at 233mm. I have overhauled this engine and soaked the pump and cleaned it out. With both cover plates off  everthing seems to be rotating properly when the spline is turned. I have removed the 2 oval shims from under the barometric pressur compensator. How many times can you turn this screw? This car sat for many years before i got it so maybe i will try to get it as close as i can and give it an itialian tune up and see what happens.

[ctaylor738]

Are you sure you are actually engaging and turning the idle mixture screw? 

You need to press in firmly and turn the thumbwheel until you feel it engage the adjuster.  Then when you turn it, you will fell a 'click' after about 1/8 of a turn.  If someone tried to adjust the mixture with the engine running, then it is jammed at full rich.  This is how my 230 was when I got it running.  The fix for me was to grab the thumbwheel with vice-grips, push it in, and turn it CCW.

Before I did this, I farted around with mine for a while thinking I was adjusting the mix.