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Flooding at idle


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How are you all doing today? I own a 1970 240z

I have a weird problem, I have changed and cleaned everything on this car and she runs very very strong, she warms up great drives very very strong but if I drive even half a mile then idle for a while, like to order a coffee or sit in a drive though, then the carbs gurgle extra fuel into the intake and bogs her down.

Once I start driving again there is hard jerking cause from the excess fuel but once I burn it off she is back to being strong.

But I just don't trust it. I've cleaned all the internal components to the carbs but was sent the wrong needles so those and the float bowl needle valves were not replaced. Other than that idk what's going on.

Any ideas?

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Have you checked your idle speed and mixture? Are the carbs balanced? Are they factory carbs? Are you running a lot of choke?

 

Lots of questions there. 

 

Sounds like it needs a tune up if it otherwise runs fine. Probably need to change the plugs and lean out the mixture screws so it doesn't bog while sitting.

 

If you can get an AFR gauge you can set it so that the car idles above about 10AFR, below that is when it starts to stumble and choke on itself. 

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Don't just lean it out per say, that is not a good idea. The mixture screws control the entire range, so leaning them out too much on the bottom can make the car run really lean on the top end.

 

You can follow john's advice and do the base procedure as in the FSM to get you a factory baseline. Once you get an AFR setup you can play around with it till it feels right.

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If your mixture adjustments are reasonably close you may want to consider other reasons for flooding:

 

  • Float adjustment,  Verify float level is set to factory specs.
  • Sticking/stuck needle valve.
  • Fuel level in bowel set to match top of jet.  If fuel level in the bowel is higher than the top of the jet fuel will just drain out through the jet!  There is a procedure for checking this using a clear plastic hose.
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So apparently I believe it was as simple as being to rich, I leaned it out, and ended up getting better idle and better performance at all rpm I didn't think it would be that simple but when I cleaned the carbs inside and out I checked all other causes and everything else looked good. It it as always was user error. And that's after paying 2 Seattle shops to do it for me, they both failed miserably

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