Rough Running after stopping

[CarlG]

About a week ago, after driving on the freeway for about 10 miles, the car started running very rough after I would stop, like at a light.  It would sputter and run poorly while idleing and on acceleration in first and second gears, but would smooth out generally about in third gear and stay smooth as long as I was driving steady.  It does not do this every time but most times I stop it does, it starts normally in the morning and is smooth for the first mile or so.  At the time the gas tank was nearly empty (although the warning light was not yet on) so I stopped and added gas, but that did not help any.  By way of history the inside of my gas tank was coated about 5 - 6 years ago and I am nearly positive the screen inside was not replaced.  Also my fuel pump was replaced a few years ago so that is nearly new.  This was a sudden occurence, there had been no warning signs previously.  Anybody got any ideas of where to look first?

1967 230sl (stick)

[ja17]

Hello,
Check your points first, sometimes they will close up, especially if the distributor cam has not been greased. If you  have a dwell meter use it otherwise, just check the gap and see if is too small or not opening at all.
There are lots of other possiblities but this is the least expensive place to start!

Joe Alexander
Blacklick, Ohio

[CarlG]

An update on this item.  I took the car in to the shop back in Jan. and they did change the points and check it out and it did clear the problem.  A few weeks later the same thing started again so I went back to the shop and they did a quick look at the plugs, which were fine, and after putting it back together it ran fine.  The mechanic stated he thought that one of the plug wires felt loose as it came off and maybe it was just not seated properly.  After a few weeks it went bad again and I pushed in all the plug wires and sure enough, #1 (the 90 degree end) popped and was loose.  But it has gotten worse, this morning I popped it back and drove about a mile and it started running poorly.  Is there any adjustment for this, or is a new plug wire the only answer?  These wires are about 9 years old.  I noticed in another post that originally the cars came with 6 straight heads so I think I will not replace with another bent one.

1967 230sl (stick)

[Cees Klumper]

In doing a minor tune-up on Peter van Es' car last weekend, we checked the resistance on his spark plug wires. Turned out the no. 1 did not make contact at all! The car was running ok though, so the spark evidently bridged a gap inside the wire. The other wires were all around 1k ohm. We replaced the cap (that was the culprit) on no. 1 with a straight one (the defective one was bent, and the marking read 5k ohm as bent ones often do).

My car a few years back developed rough running problems and it turned out to be the wires. So it is worthwhile to either check the resistanc on them, or replace them altogether with a new set if they are 9 years old.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[ChrisInNashville]

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[ChrisInNashville]

Joe & Cees,

Is it possible that there is a fuel problem here.   Could bad gas, cause this despite a recoated tank and relatively new pump?

See you in July in Ohio!

[Naj ✝︎]

Carl,
You may have an air leak, worse at idling than higher rpm.
Check the manifolds to head nuts. You may have to remove the heat shield get at all of them.

naj

65 230SL
68 280SL