I have an 85 12a, Auto, just rebuilt with zero miles. It was rebuilt by KDR. It will start basically with no problem but it will not stay running without keeping my foot on the gas or keeping the choke pulled all the way out. As soon as I let off the gas it dies. If I start pumping the gas it will stay running. If I put it in gear it instantly dies. Ant Ideas? I have had this car for a year now and I really want to drive it. Thanks, Vic

 

Try adjusting the carb. Check all your fuel system; pump, filter,lines, ect. Does it run well with your foot on the gas? If so i would supect a carb out of adjustment. If it runs like crap with your foot on it/choke out it may have a vaccum leak. check all the hoses, gaskets, ect.

Good luck!

 

Turn the idle speed screw in until it will idle on it's own. Then set the idle mixture screw. Follow the Haynes manual, or ask here for help. Then go back and set the idle to 750 rpm.
hanman

 

Isn't the idle mixture screw covered with some kind of cover? The car will run by pumping the gas but when it gets up to temp it seems to run a little better. I still have to keep my foot on the gas but not as hard. I've checked all the fuel system: New stock fuel pump, relay. Fuel lines are new, new gas filter and also an inline gas filter by the carb. Fuel is the right level in the bowl (half way). I've checked all the vac hoses several times I replaced all vac hoses with silicone. One other thing I just thought of...what is the black plastic molded plate that sits under the carb for? Mine is broke..half of it is on the car the other half is in my shed. Do I need this thing? What does it do? Should I take the rest of it off? Could it cause a vac leak? Thanks, Vic

 

That's the gasket between the carb and the intake manifold! That certainly could cause a vacuum leak.

They're expensive, but you can get a normal gasket to replace it for 2 bucks from Mazdatrix. Check it out:

http://www.mazdatrix.com/c-3.htm

Originally, but most of them are gone by now. You can take it off yourself if it's not. Just follow the instructions in the Haynes manual, you'll know right away if it's the problem. Sounds to me like that gasket is your trouble though.

 

Thanks...For some reason I completely forgot about it. I've spent so many hours staring at the engine and never even thought about that thing. The mixture screw cover is still on my carb. The carb is only about 3 years old. It was bought from mazda by the guy who owned the car before me. Boy my heart is racing right now just thinking about getting this gasket done...YHEA ME!!!!!! Thanks

 

No problem, hopefully that is in fact your problem and you get your rotary rocket on the road again soon!

 

BTW My rocket is silver too..

 

Sweet!!

Hurry up then, we need as many silver rockets as possible out there!