1989 Mazda B2200. I have had if for several months and is said to have a rebuilt engine about 50 K miles ago in it .. it has been running fine and in fact ran great at 80 MPH going home the evening before.... well, it did have a "flat spot" if wound out at high RPM in first and second which I figured was a fuel delivery problem. Anyway, the other day I was started out and about one block from home when it would not accelerate. I could smell gas. I went back home and removed the air cleaner. Gas was every where. It will start and run fine as long as you do not accelerate. Gas blows back up through the carb when you try to accelerate. Timing is correct and compression is good. I do not want to take the carb apart unless no other options. Does this sound like a carb problem or is there any other possibility I can check out ? Thanks for any suggestions you may have.

 

sounds like a bad accelerator pump in the carb

 

Just wanted to offer my experience for what it is worth. I just recently rebuilt the fuel sending unit in the gas tank of my 1989 Mazda B2200. By the waythe fuel sending unit not workingis an issue of wear on the linkage at the rub point of the linkage where the linkage is crimped which causes the rheostat wiper not to contact the rheostat windings with enough force to make contact. I fixed it by putting a copper shim in the joint. Anyway before I did this repair I had a problem of erratic running (difficult starting)when the engine was cold and had to set the Idle up so it would run/start cold and then it idled too fast when warmed up. When I removed the gas tank todo the fuel gaugesending unit repairI replaced the rubber fuel lines going to the tank from the frame.When the car was started after replacing the tank it ran very differently. I adjusted the idle down and the problem with not starting and the highidle went away. I attribute the problem to hardened rubber in the old fuel line and small cracks which caused the gas not to be able to be sucked from the tank (air getting into the fuel line)until the lines would swell after fuel began to flow in them when warmed up. With a car this old the fuel rubber lines should be replaced. It can make a big difference in how the engine runs.

 

Toddluck: Thanks for input. I was hoping I would not have to pull the carb apart. I am not challenging your answer but am trying to understand how the pump can be bad as there is a large amount of gas being blown back up the carb when the gas pedal is pushed so I was thinking the acclerator pump was OK as it is pumping gas... I fear I will have to pull the carb apart ..thanks

LDK: Thanks for your experience My gas gauge is not working either and I planned to drop the tank once warmer weather arrived. I will check and replace the hoses when I do it.. seems many of the old Mazda gas gauges fail.... good tip.. thanks..

 

with all that high rpm. you probley sucked something passed the fuel filter and it's not letting the float valve close fully. or an intake valve is hanging open. if the enginesnot missing, i would check the float valve first.

 

if your accel pump is bad the fuel will pass the seal in it.........a bad float level will do the same thing until it ruins your accel pump

 

Thanks for all the inputs.. once it gets warm enough I will take the valve cover off to make sure it is not a hung valve then look into the carb repair It does start and idle just fine..just that popping gas back up the carb usually is timing related from my limited experiences.
Thanks again to all that replied..
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I may have found the problem !! I borrowed a vacuum pump at Auto Zone to test the vacuum advance on the distributor and it does not appear to be working. I also tested an old dist from a 1987 B2000 and that diapram did pull back the link when vacuum was applied. Unfortunately, the 87 wont fit the 89 so I am going to order the diaphram on Monday when the dealer is open (I cannot locate one in parts stores) and I will update this once I get the part.

 

The 87 vacuum can won't fit the '89 distributor or the '87 distributor won't fit into the '89 engine?

I know my mechanic temprorarily installed an '89 distributor into my '88 to troubleshoot mine.

 

Update :
to Cusser: I took the 87 diaphram and lever and put it on the 89. the 87 was different from the 89 but it did allow me to at least get it to run and with patience, get around.

Update: You can not get a vacuum advance diapham from dealer .. only new distributoer and it costs a pretty penny.. I got a replacement used distributer on Ebay and the vacuum advance on it works (checked with vacuum pump loaner from Auto Zone). The truck now accelerates nicely .. for a while (to mid range RPM) but then starves or acts like it is not getting gas but no popping back through the carb. I guess I may have had two problems.. possible the vacuum advance was already broken?? In any event, I am going to see if I can put a gas supply directly to the carb to rule out tank, lines, etc and if that doesn't help I guess it is carb rebuild or replacement time.
Just can't understand how it went from running so great to running like crap overnight. I am able to drive it but carefully as it can barely get out of its own way in a hurry but, with patience and tender gas pedal pressure, I can get to 60 MPH in 5th gear...
I have checked and rechecked the vacuum lines and all that and can't find anything out of place. Would appreciate any input
Thanks