1970 250C won't idle

[Don L]

I have a nice 1970 250C,ENGINE BLOCK NO. 130923-12-002036 serial no. 114023-12-002047. I don' know if it is a M130 engine. It starts good and it takes gas good when accelerated,does not backfire,but has to be pumped some to KEEP IT RUNNING. The vacuum regulator does not work. I took the top of the carbs off and found that the rear accelarater pump is not working. Any help would be appreciated ! Thanks Don L

[230/8]

Sounds like you may need to learn a whole lot about Zeniths. You have an M130. Try searching this site for threads about rebuilding and adjusting Zeniths. Lots are here filled and they with good data on this almost lost art.

230/8

[Don L]

I have been trying to learn about the Zeniths. I have downloaded a lot of info. off of this forum. I really like this 250 and I want to keep it. I live in New Castle Indiana, about 50 miles east of Indianapolis IN. I have not had any luck on finding a mechanic in this area that can help me,can I purchase a pump for rear carb. Don L

[230/8]

You can get carb-kits and accelerator pumps here:

http://www.***************/search/product.aspx?sid=ipyzzo45qw3kqez5axfrzxn5&makeid=800016@Mercedes&modelid=1193059@250C&year=1970&cid=22@Fuel%20%26%20Air%20System&gid=5905@Carburetor%20Parts

Look at this site for a Zenith manual:

http://www.jaimekop.com/

Click on carb manual to the left.

Get a CD ROM manual for your car here:

http://www.classictechlit.mbusa.com/MB/

They are $20 plus shipping. The carb data is located in the section for the 250. You can also get a paper copy of the Zenith manual from them, you need to search the site for it; $20 as I recall.

Get the tools you need to adjust the Zeniths here:

http://www.baumtools.com/

Click on products and search keyword Zenith. You will need a bonnet adaptor for the air horn and a unisyn-style balancing tool. If you remove the carbs to rebuild them the special carb nut wrench will be handy to get at the rear-side carb nuts. I have no idea what these cost, I got mine years ago at a Solex shop in Vienna...cost about $6 for the bonnet. Probably ten times that today.

Search and read all the various threads for adjusting and balancing on this site. Rebuilding is easy. Adjusting is harder and almost impossible without proper tools. Do not believe anyone who says you can use a rubber hose in the air horn to balance a pair of Zeniths.

Good luck,

230/8

[Don L]

Thanks 230/8 Don L

[Blue 72 250]

Don - Welcome to the forum.

I have gone through the "normal" issues with my zenith INAT carbs in the last few months. I am happy to help with any specific advice.

You need to get the vac. Dashpot working again, or find a replacement. As for the accel. pump... Did you pull the rubber boot from the bottom to see if it is soft? What about part # 122 on the diagram posted in this link Zenith 35/40 INAT question you will want to make sure that it free from buildup. I like to pull it out with a pair of hemostats and burn it with a cigrette lighter.

If you are still having a problem after that, I would think about a rebuild.

Have fun