My cars and I have a silent agreement. I take good care of them, and they agree always to get me home. As evidence of that bond, my cars have a remarkable record of only failing within walking distance of home. This week was no exception.
As I turned onto my street returning from our club’s pre-autumn outing, my 2CV6 started having trouble idling. Accelerating and driving were no problem, but as soon as I would stop, the car would stumble and die. It would fire back up immediately, and as long as I tickled the throttle, I could keep it running. Negotiating the reversing portion of a fiddly parking manoeuvre was challenging, but I managed it.
I did a quick Google search. Discussions on various internet Forums pointed to a blocked idle jet in the double-barreled carburetor. I referred to the Haynes repair manual (every 2CV owner should have one) but I had some difficulty mapping the carb models and determining the exact location of the suspect jet. However, one of the marvelous things about the internet is that someone somewhere has faced the same problem you are facing, and has shared some priceless info. In this case, I landed on a site where a German 2CV owner had posted a series of labeled photographs of his carb (Thank you Norbert!). Sure enough, it was the same as mine.
Armed with this valuable information, I set to work.
The jet now was easy to identify, just below and to the left of the fuel inlet pipe.
Access was not terribly easy. I could not get a blade screwdriver in from the front, due to the oil breather being in the way. My 8 mm box-end wrench (ring wrench) was too thick to fit past the edge of the fuel inlet. The open end of that wrench was possible, but I did not like the angle, and did not want to round off the brass jet. However, another site had told me that I could safely remove some metal from the side of the fuel inlet.
Searching my toolbox, I found an old points file (for cleaning up ignition contacts). This was just slim enough to slip behind the head of the jet, and file against the corner of the fuel inlet body. With just a few strokes, the job was done, and my ring wrench now slipped cleanly and securely over the hex head of the jet.
Almost no force was required to loosen the jet. At that point, I removed the wrench, and unscrewed the jet with my fingers. Of course, the touchy point is not dropping the jet once it is free of its threads. As you can see in the photos, the threads are quite long, so you have time to prepare yourself.
Taking the jet over to the workbench, I could see that the end did not look very clean.
My reading on the web had told me that I did not want to poke anything into the jet if I could avoid it. This is because the orifice in the jet is very carefully calibrated (i.e. it is a precise size) and the body is made of soft brass. So, if you are too aggressive with a fine steel wire, you can accidentally change the diameter of the hole.
My weapon of choice then was spray cleaner. In my case, I used brake cleaner (because I had it handy), but there also exists special carb cleaner. I sprayed well, through all the available holes, and then let the jet sit to soak in a small puddle of the cleaner.
After a good soak (5-10 minutes) I used some compressed air to blow through all the various holes.
Here is the result (before and after).
Feeling pretty confident, I reinstalled the jet with my fingers, then gave it a slight snug with the 8 mm wrench. Being made of brass, you do not want to over-tighten it, as you may damage the threads. On the other hand, you do not want the jet to vibrate loose and fall out! (I will re-check the tightness after a few days, without trying to make it any tighter).
Now came the moment of truth. I climbed in behind the wheel, and twisted the key. My motor fired up immediately, and quickly assumed a slow, smooth idle. Perfect!
People sometimes ask me why I want to drive a “fiddly old car”, when a modern car “hardly ever” goes wrong. Frankly, it is precisely because a 2CV tells me when it needs something, and then generally makes it pretty easy to satisfy its needs. I am quite happy to continue to our relationship.