Rough idle, very loud backfires, and now won't start

[amg5872]

Hi, just thought I would provide an update on this if anyone is interested. Well, at least I will try to convey what the shop told me. They told me there is a component on the rear carburetor that was loose or out of adjustment or something such that the car had no choke at all. It also turned out the points needed adjustment as when the car would heat up the points would basically get stuck in a closed position. I'm working on more detail and will update when I have it but thought I would share what little I know so far in case this helps others. Thanks for all of the help, suggestions, ideas.

 

[Koopman]

Backfire?

Hi Ameer:
My son fired up his 2000CS for the first time since 1999 after a complete restoration and engine and tranny rebuilt. Fired up at first try but backfired quite a bit. Turned out to be a choke adjustment.
Who knows?
Koopman

 

[ECA90049]

The issue with the tachometer diving to zero happens only when I let off the gas, for example, if I am slowing down for a stop sign. If I don't nurse the gas, the rpms will want to dive straight down to zero. I'm starting to become a very good two-foot driver. It generally doesn't happen at all if I am in gear (although a few times while driving the tachometer has just blipped down and I've felt like I lost power for just a fraction of second). But generally the main problem is that if the car is in neutral or if the car is in gear and the clutch is pressed the gas needs to be nursed or else the tachometer will go straight down to zero and the car will gurgle and spit and try to die. I currently have a second shop taking a shot at diagnosing...

I have the same thing going on with my 1971 E9. Starts right up, but if I don't rev the engine it goes to zero and dies. Someone mentioned it might be an idle valve malfunction. Have you had any luck fixing it?