1986 Mazda B2000 Engine Performance Problems- hesitation

I had B200 that had the same problem. There are three reed valves in the front of the air cleaner that control gases from the exhaust system. They are a dealer item only, well they were when I had mine. It's worth checking into. You also might check the vacuume advance diafram on the distributor this also causes hesitation.
Good luck,
Tony.

Yes it does do it around 65mph. Is there a way to test the component? About how much does it cost? What would some other symtoms be? The engine kind of does it (hesitates) around any speed that is around 2000-3500 rpms while I am steady on the throttle and it doesnt matter whether the engine is under load or not it still does it. The only time that it doesnt seem to do it is when the engine is cold/not warmed up. I feel it has to do with the carb. Any more help would be appreciative. Thanks ALOT![/B]

My suggestion would be to replace the carburetor with one from another Mazda, preferably one that just found it's way to a junkyard. Most of the cars that are brought in from accidents will have good working components.

Sorry, but I forgot to mention this. My Mazda b2000 had the same problem when I bought it used. The problem turned out to be a broken, cross-threaded spark-plug in the number 3 cylinder. Check that your spark-plugs are all in correctly and gaped, as that WILL cause hesitation in the engine. Also a side note, you don't HAVE to replace the reed valves usually, just take the filters out of the rubber gromit and the metal casing (don't worry about breaking anything but the rubber if it's dry, they are made to come apart) and wash out the filters with a strong anti oil dish soap. They should be a light brown when clean. When they are dry, put it all back together and fire it up! You should see a noticeable improvement in performance if they were oily or full of dead bug parts.

Hi, I realize this thread is older. I am having the same issues, jerking, hesitating, occasional stalling at lower RPM, but only in gear and driving, from second gear (5 speed standard) to 65MPH in 5th. It seemed like vapor lock at first (100 degrees) but then just does it even with the engine temperature and weather cool. I replaced the spark plugs and ignition wires. I am having a hard time finding the reed valves, to clean or replace (at the front of the air filter housing?) Also, could this possibly be a clogged fuel filter or fuel pump failing? Just curious what my next steps should be. Thanks for any help you can provide, I appreciate your time. :) P.S. It has a new timing belt, water pump, starter, coolant hoses, thermostat, not that this is relevant, just trying to supply information.