hey all-
so, i've got a 1982 euro model 250 (123 body) with a Solex 4A1 carb, auto tranny, and a 123.921 6-cylinder gas motor that's got 261k on the clock.

i've only put 100 miles or so on since purchasing her last June, because she's got a big hesitation / bog when you try to accelerate. she idles just fine, but when trying to pull away from a stop, you touch that pedal to about 1/8-1/4 throttle, and she goes silent, acts like she's dead or is going to die.
if you try to coax her, or let off, or floor it, she'll usually fight her way to a good fast rev, but it's seriously dangerous trying to get through an intersection!

i've capped off or tested every vacuum line, and it sure seems the accelerator pump is spraying as she should when the linkage is blipped.
i've read a bit on the forum about these carbs being infamous, so i guess i'm leaning towards starting there.

how do you tell if your carb is warped?
do my symptoms sound most like that, or would you suspect floats?
nasty jets?
or ?

(dunno if it makes any difference, but: sometimes she'll die when you put her in gear, and there's a good 3-4 second pause before she'll go in gear from Park to Drive. Vacuum test on the tranny/modulator line holds good).

i'd sure appreciate some help.

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-lee
'83 300CDT (286k)

former proud owner of:
'85 mercedes euro 300TD
'80 mercedes 300TD
'77 mercedes 280e
'80 mercedes euro 250
'82 mercedes euro 250

You can try to spray some WD 40 type of product by the gaskets, and see if idle changes.

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It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D

sounds like a accelerator pump problem to me. You need a good squirt from the pump. Check it when the car is off, remove air filter and open the choke. Then move the throttle and see if you are getting the squirt.

You say it "seems" like the accelerator pump is squrting. Can you clarify that?

Been a while since I messed with these, but there are air restrictor plates above the secondaries that need to open in sync with the secondary throttle plates. If these are stuck open or open too quickly, it will all but kill the engine because it's getting massive amounts of air but not much gas.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

I'll keep an eye on this thread as I have the same issue on my Solex 4A1 280C.
I wish I had the know-how to rig up an EFI system on it.

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Nathan
'74 280C - gone to a new home for the finishing it deserves.
'64 356SC
'74 914 2.0

I hear you. My 73 280C is just about worthless with that q jet knock-off. My mechanic is thinking of putting a q jet on it with very little modification and much cheaper too. But to answer the question, no, your carb is not trying to kill you, just embarrass you. Beware of being first in line at a red light, that's when most of my problems with choking happen.

IMO, It may be cheaper to fix it and make it work, but it will be easier to replace it with a kit or something. Good luck.

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Die auto ist immer kaput...

well now-
after coating everywhere with WD-40 and not being able to effect a change in her idle, i had another look at the accelerator pump.

when i'd inspected it before, i'd just been told just to look for a stream of gas shootin' when i blipped the throttle. NOW with y'all leaning heavily that direction, i reapproached it and looked at the adjustment. the lever was resting very heavily on the pump's piston, such that the piston was about halfway depressed.

i adjusted the nut ((see photo) nut shown in the background)) til the lever was *just* barely touching the piston, and then turned the screw (in the foreground) in till it was *just* barely touching the pump cover plate. doing so has definitely improved my symptoms, though not totally fixed the problem.

anybody know whether i did that adjustment right?
or got any more good ideas?

Attached Thumbnails

 

__________________
-lee
'83 300CDT (286k)

former proud owner of:
'85 mercedes euro 300TD
'80 mercedes 300TD
'77 mercedes 280e
'80 mercedes euro 250
'82 mercedes euro 250

the next thing to do is check the "aim" of the squirt. You will want it pointed at the throttle plate on the side that it opens. If the squirt hits the side of the venturi you will not get the appropriate action. A new set of seals on the pump will also increase amount of squirt.

I would also consider checking the timing and plugs to confirm a strong spark at proper time.