Mechanics

B2000 ENGINE PERFORMANCE PROBLEMS- HESITATION

1986 Mazda Truck

Hey, I have a 1986 Mazda b2000 LX short bed 5 speed manual transmission with only 80,000 miles. It runs great other than my small engine problem. The engine hesitates/shakes/jerks/pulsates when at around 2400 rpm- 3300 rpm when cruising steadily on the gas(this doesnt happen when the engine is cold, only after it reaches normal operating temperature). I checked out a Technical Service Bullitin about the subject on " All Data" and " Shop Key" and it says it needs some new modified parts. The problem is within the EGR System is what it is leading me to? Any help/suggestions would be very appreciative. Thanks alot.V
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1989CamaroRS
February 9, 2006.



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.

Tiny
Glassman55tb
Feb 10, 2006.
That sounds like a perfect symptom of the idle mixture solenoid. The sensor cannot be seen from the outside of the carb. The only thing you can see is two green wires coming out of the top of the carb when the air cleaner is off. Let me guess you have a stuble or hick-up around 100kph/65mph?

This could be a good posiblity

Cosmo. Mazda Tech

Tiny
Cosmo
Feb 13, 2006.
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]

Tiny
1989CamaroRS
Feb 14, 2006.
There is no real way to test this component. It was a TSB about ten years ago. You can replace it on the vehicle, you only need to take the top of the carb apart. This can be done, but you should take it to a Mazda dealer unless you are very very very very familiar with Mazda carbs and their settings, because after this you will need to set-up the carb and all the mixture settings.

Cosmo. Mazda Tech

Tiny
Cosmo
Feb 14, 2006.
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.

Tiny
HellCat18
Mar 29, 2007.
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.
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Tiny
HellCat18
Mar 30, 2007.
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.

Tiny
86MazdaB2000
Aug 8, 2012.

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