210 cold start issue

[molly210]

I have a '79 210 with stock Hitachi carb. It's been a daily driver for years. I recently rebuilt the carb and cleaned the nozzles, which solved some jerky acceleration issues I was having. However, after that, I've been having issues with my cold start. Choke seems to be properly adjusted - butterfly plate fully closed and fully open when warm. However, I struggle to get the car to enter a normal high idle in a cold condition. It reluctantly fires up and chugs to life, spewing lots of rich smelling exhaust in the process. rpms are very low and it wants to die. After a minute or so, if I give it lots of gas, RPMs will go up, but nowhere near the high idle I used to get during a cold start. Then, once warm, it runs like a dream. It will re-start easily if warm and run fine.

 

I confirmed there's a strong spark from the ignition coil at start. Also confirmed that distributor rotor points towards plug #1 at 10 deg from TDC. I've tried adjusting the fast idle screw both ways, but it doesn't improve cold start. If I move the screw too far in either direction, it won't start at all. 

 

Other potentially relevant information... the car was stolen last year, and when I got it back my ignition switch got pretty messed up. I am still finding other weird things that got messed up during that period... so nothing's off the table here. 

 

Appreciate the help.

[datzenmike]

Spray WD-40 all over the rear of the carburetor. Hold the throttle half open to release the interlock and pull the choke full closed and open several times. Watch where the linkages go down near the throttle shaft.

 

There should be a fast idle cam that lifts up and holds the throttle slightly open when the choke is pulled closed and freely drops down when the choke is open. You have to hold the throttle part open for this to work. The fast idle cam will look something like this...

 

 

 

As you can see with difficulty, there are steps on the underside that the throttle closes on slowly lowering the idle as the choke moves toward off or open.

 

I don't have a 210 carburetor so you will have to see what isn't right. If it was apart it may have a piece of linkage on backwards.

[molly210]

Thank you. 

Quote

Spray WD-40 all over the rear of the carburetor. Hold the throttle half open to release the interlock and pull the choke full closed and open several times. 

 

Ok did this ^^. Linkages seemed to all be moving freely. However, the cam steps on this one are inside the choke housing, so I couldn't watch them operate. I'll take it apart more tomorrow. Just greasing up the linkages didn't help the situation, unfortunately.

 

I do recall when I took the choke apart before that the cam steps were VERY faint - almost invisible. Is it possible the steps have worn down to the point that they don't reliably catch? 

 

 

[datzenmike]

It would still be a ramp and work I would think. Can you see the piece that sits on the steps that holds the throttle open

[molly210]

Thank you datzenmike. I did a visual inspection of linkages vs blow out diagram in manual, and can't seem to spot anything off. Here's the inside of my electric choke w/ cam "steps". I think you're right - the steps on the cam do seem to catch, despite being faint. Also added some linkage photos.... see anything off? 

 

https://imgur.com/a/ugSDWwA

(.. hope these images come thru)

 

[datzenmike]

 

Only one picture shows. Above.

 

Should have the covering part that has the electric heater inside it below...

 

 

 

 

 

The back side has a wound up spring and that J shape must engage that part on yours that sticks out.

[molly210]

Thanks - yes, I had taken the cover off to view it better. The spring was in the right spot when I removed it. And choke plate was operating correctly - completely closed when cold and fully open when warm. But for some reason the idle is SUPER rough when cold (wants to die). 

[datzenmike]

Perhaps the fast idle wasn't working. On a cold start the idle would normally be 1,800-2,200 RPM. With the choke held fully closed you can bend that down rod that goes to the fast idle to adjust the idle speed.

[molly210]

Ok - is bending the rod different/preferable to adjusting the fast idle screw?

[datzenmike]

The set screw won't do anything if the fast idle cam isn't moving. It's set at the factory for the proper fast idle speed and doesn't need adjustment.

 

Hold the choke full closed. (you will likely have to open the throttle slightly to release it first) Then adjust rod so set screw is on highest step.