Engine stumbling - cold start air noisey??

[rogerh113]

Hello,

Went on my weekly 30 mile jaunt last week and the car ran flawlessly, but when I went to start my '66 230SL this week the engine kicks over but stumbles. I did fill up the tank before the trip, and had no problems on the trip (stopped 3 times with no restart issues), so probably not the gas.  The engine has a low stumbly idle (generally runs at 1K just after start, and now at around 5) and very hesitant/difficult to rev (so I didn't push it).  Hadn't changed the plugs in a while, but that did not help.  The one thing that I notice is that the air intake for the cold start (on top of the injection pump) is much louder than I have ever noticed before.  Is there a typical failure mechanism there that could be dumping too much air into the engine and causing this??  

No obvious loose lines or electrical connections - I hope it is not serious...

Regards -- Roger

[glennard]

Unscrew the filter and stop the air flow into the intake manifold---see what happens.

[rogerh113]

I'll give it a shot - not sure what NO air will do, but it is worth a test!!  I've rebuilt the cold start before, but a long time ago so I don't remember how the air flow is actuated.  Hopefully I can find a schematic that will help.

The weather here in the California bay area is stunning, and I need to get back on the road!!

Thanks -- Roger

[glennard]

The air filter on the FI pump- about 1 1/4" in dia.  The thermo closes this air to the CSV when the temp gets to-whatever the specs say- 70 C?

[rogerh113]

Rebuilt the cold start unit, and things seem pretty much back to normal (aside from a bit of further tweeking needed on the idle screw, etc).

Regards -- Roger