I have an aisan carb on my 81 22R. i rebuilt it and it still seems to idle bad. im pretty sure its the carb and not timing. are there any re-jet kits or ideas out there for this carb? i want to stick with this carb as i have heard that it is better than a weber or a holley for this truck.
carb help
- Thread starter kj1074
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Howdy! What's it doing? Ruff idle, stalls out, speed varies, no power to start rolling?? Did you reset the idle mix screw? General theory on that is to start with it about 2.5 - 3 turns out from being all the way in (gently). Adjust in or out from there to get the highest idle speed when the engine is warmed up. From that point I usually turn it back in just 1/4 turn, then adjust the idle speed screw to what you want. John
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- #3
it has power and is pretty solid. its just hard to start when hot and idles rough. the a/f screw is about 2.5 out. ive tried in all kinds of places for a/f and idle and timng. i just opened up the exhaust and i think that may have somthing to do with it. it seems like its just a POS carb. i had a rochester on the jeep and it ran terrible, switched to a holley and now it runs great. ive heard that going to a holley or a weber is not much better than this aisan. has anyone else exprerienced problems with these aisans?
the power differance with the weber is quite noticeable,much easier to tune to.sounds like the fuel shut off valve might be malfunctioning on your carb,they get sticky or the o-rings go bad on them.or you have a bad vacuumn leak.the weber is GREAT,but you have to take the time to properly tune them,in the 4 that I have put on they are never on right out of the box,there are main jets idle jets,and accelorator pump discharge nozzles that can all be tuned.the only downfall to the weber are they are moisture sensitive,not so much the electric choke ones because of the heat from the choke coil warming the carb,but the manual choke ones.
another thing to check is the aap(auxilary accelarator pump)sometimes they dont hold vacuum and keep injecting fuel when they arent supposed to.I had on that a pinhole in the diaphram once that allowed fuel to get past and sucked into the vacuum hoes that was attached to it causing a rough idle.fsm should show you how to test that too.but I have had trouble with the fuel shut off valve even though it seemed to work when taken off(it made the clicking noise)could be the circuit is plugged up.I really like the weber a lot better much simpler.once you have them tuned in the reliability is great.I noticed a 1-2 mpg increase to.I have heard so many people say they are junk untill they hear the ones i have tuned!Like I said great carb but you HAVE TO TUNE THEM IN.not a bolt on and go deal must buy the jet kit with the carb.I have seen the weber kits go on ebay for 300 and the jet kit is about 50-60 bucks.verses 300 for a rebuilt aisan.I know what i would do.You can rebuild the aisan yourself but the problem I always run into rebuilding any carb are worn out throttle shafts causing vacuum leaks.
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- #7
yea man i know what i would do too, if i had $300+!! (im a college student) i did a new diagphram for the accelarator pump. when you say worn out throttle shafts what exactle do you mean? the guy before me obviously pulled the shafts out cause there are different screws holding the actual throttle plates on the shafts. i bet he mucked it up in there and its causing vacuum leaks. what do you think?
if it doesnt want to restart when hot it has to be flooding out,check when engine is runing that no fuel is coming out of the accelorater pump or the aap(when engine is idleing look down carburator throat)then rev the engine fuel should squirt out of the accelorator pump and if the engine is cold out of the aap remember the aap and the accelorator pump are 2 different things.then when engine is warm the aap should stop squirting fuel.the only other thing are to check for vacuum leaks by spraying brake cleaner around when engine is idleing and listen for rpm changes.by worn throttle shafts i mean sloppyness in the shaft where it goes through the carb housing.
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- #9
the aap is on the drivers side of the carb and the accel pump is on the passenger side right? how would i know if the aap is pumping fuel when it is hot? i can see when the accel pump does, as it squirts pretty much all the time. would the aap pump out of the same place? im a little confused on how the aap works are where it is routed too.