engine stall after overrunning

[Ron]

After a long deceleration, my engine will stall.  I can avoid this by a quick hit to the accelerator when clutch pedal is pressed, but usually I'm braking too.  I can mitigate this somewhat by richening the idle, but that causes black smoke at normal idle.  This is a manual car and the little diaphragm that slows the linkage back to idle is there, working, and adjusted.  That diaphragm runs out of time for the cases I'm having problems with, like a long coast down a mountain.

Any ideas where to try next, or is this just the nature of the beast? 

Ron

[ja17]

Hello Ron,

You should be able to adjust this problem out.  Assuiming the linkages are correct, you may want to double check the fuel mixture at idle.  Also if your car has the deceleration solenoid on the IP, try disconnecting it and going for a test drive.

[don p]

I had the same problem. I have 2 Solenoids on my FIP and was told to unhook the leads on the bottom one. this solved the problem so you might try that if you have the 2 solenoid injection pump.

[Ron]

I thought I'd bump this thread and give an update.  I did fix the problem, well if you want to call it a fix.  But first, thanks for the two replies, from Don and Joe. My car does not have the second solenoid.  However, it has an R18 pump, not the correct R11, so that's one mark against getting it all correct.  The car came with engine out, so I don't know if this R18 pump ever worked well.

For two months, I've played with the linkage, idle mixture, rack mixture (via shims on WRD), throttle damper (this is a manual car, and no damper came on it, but I installed one) and idle air.  Nothing really changed the problem, a stall after a long run down a hill with foot off the gas. If I ran the idle rich, it seemed to improve a bit, but it still would stall.  It started right up afterwards, so just popping the clutch if the car were still moving got it going.  Additionally, I noticed that a small blip of the throttle before pushing in the clutch would preclude the stall.

So even though the linkage was correct, and all the other running characteristics were fine (start, stop, acceleration., hot, cold, made no difference) I decided to adjust the rod to the FIP off the spec.  I made it longer.  I got the car warm, at idle, running fine, and then adjusted the rod about 3 mm longer.  This sets the FIP off idle and the engine sped up.  I lowered the idle (leaned mixture screw) to bring it back down, and off for a drive: no stalling.  The RPMs still drop below idle a bit when clutch is pressed after overrunning, to just about 500 (normally 800), but the engine pops back up and idles fine.

Finally!  My guess is that the FIP has it's lever in poor adjustment.  There is no set screw on this lever, like is mentioned on the threads for other pumps.  

So for now, it works.  I'm going to adjust the fuel air mixture after buying a meter.  ('wish Harbor Freight had a cheap one, all I want to do is this one car)

BTW, in the process of all the adjusting, with the FIP off the linkage, I noticed that full throttle on the FIP lever has more travel than the linkage will allow.  Is this normal???  Am I missing full fueling?  And coming back to idle from throttle open, there is a bit of resistance on the FIP lever going that last few mm to the internal idle stop.

So to recap, my adjusted linkage does not allow the FIP lever to come back to idle position (about 3mm) nor does it allow the FIP lever to go to full throttle position (about 1 cm).

Any comments?  Should I be looking for an R11 pump?  Ron

[ja17]

Hello Ron,

Interesting, a R18 280SL injection pump on your 230SL.   

I suspected that these pumps could be interchanged on all these W113 cars if you knew enough about the injection to make the needed adjustments.

The lengthening of the rod from the IP improved the problem. This tells me your pump is lean at lower rpms and needs more fuel.

Make sure your fuel delivery pressure and volume is correct and your fuel filter is clear. Check your ingnition timing at an idle also. If the timing is not right, your engine vacuume will be low and your linkage dashpot will not work correctly.

Anyway, with that pump you will most likely need some radical adjustments (rack adjustments). Or maybe the previous owner already leaned it out too far. After checking everything out, with warmed engine do a split linkage CO test at idle, 2000 and 3,000rpms. Report back when you can.