cleksutin

Ok here's the basics:

1979 Mazda rx7, bone stock.. no crazy mods, even has the original exhaust.

Here's the issue:

so I took the air horn off the nikki today and found one of those little hangers for the float valves missing. So I replaced it, put the carb back together and BAM she was purring like a kitten! I was so happy! On to step two: I drop the gas tank and clear the fuel pick-up line, thinks are looking good right? So I re-install the tank, reconnect the lines, slide into the drivers seat and turn the key.... Now keep in mind, this car was running two hours ago... And gas comes pouring out of the top of the carb! I have no idea what happened here. I pulled the air horn back off, and everything with the floats looks ok, but obviously the valves aren't closing and preventing the fuel from pouring through, plus it's acting line the fuel pump is pushing at a very high PSI, put the pressure tester says 3 psi. Needless to say I'm now very confused. Any takers?

leks

DivinDriver

iTrader: (15)

Easy one; you had a float needle get hung up. Happens sometimes esp. with new needles or if the little wire 'hanger' gets in the way of the hinge.

Sometimes smacking the carb on top the bowl with a plastic hammer or screwdriver handle will clear it, but the best way to prevent it is to lighylt burnish the corners of the new needle before installing. And make sure the little retainer hanger is clear of getting stuck.

Other possibilities are that you lost the pin or spring from a needle (but that's usually visible) or some crud released from your tank work made it through the screens and filter and stuck on the needle or seat, preventing it's closing.

cleksutin

Is sand paper acceptable for this?

it just seems very odd that the car would be running fine with the pump running from an auxillary gas tank, but be thrown this far out of whack by reconnecting the the original tank. I guess I'll take the carb apart again and see what happens.

DivinDriver

iTrader: (15)

It doesn't need sandpaper; burnishing involves lightly rubbing the corner edges over a smooth, harder piece of metal. The back of a stainless steel spoon works well. You know you've done it enough when the edges become very bright and shiny.

The idea is not to remove material, but to simply flatten down the finish on those long corners so they slide more freely.

cleksutin

Some one from my local rotary club also mentioned something about the floats becoming saturated. I am by no means a carb expert, but how would you prevent this from happening in the future?

DivinDriver

iTrader: (15)

Float saturation is not that common of a problem. There's no 'prevention' for it though, as it's caused by failure of the outer sealing layer of the float. All you can do in that case is replace the float.