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Discussion Starter · #1 ·
Hello guys this is a first time of me finding this with my Holley carburetor and out of all my years of tuning and troubleshooting my Holley carbs I have never seen anything like this before. I found this a few weeks back while I had my air cleaner off and was checking some things over and found it again today.

What I found was that the rear passenger side main air bleed was full with fuel. I had to take a second take as my shop light was all I can get a good light with but I took a shop towel and tried to dab it and sure enough I could see a wet spot and it was fuel. I rebuilt the carb back in March and it was as clean as can be and I used carb cleaner and my air compressor and it did fine. I have correct fuel pressure at 5.5 psi with my regulator.

I have looked all over my main body back then and it showed no signs of fuel spillage anywhere and everything was as dry as can be. I sprayed the air bleed out with carb cleaner and then blew a quick shot of air into it and it was all dry naturally. I did not have any issues with the carb running bad or any driving problems. Well today I had my air cleaner off again looking over things and checking stuff like I normally do on a regular basis and once again I had fuel that was full to the top of my passenger side main air bleed.

To verify I took a toothpick and I stuck it in and used a big magnifying glass and sure enough the toothpick soaked up the fuel and I could see it on my finger. I looked with my light down in the air bleed and there no sign of anything being plugged up. I even recently had my truck out on a few wide open throttle runs and there was no issues with anything on how it ran. I looked at my air vent and there was no signs of any fuel spilling out.

The metering blocks I used on a previous carb and they worked fine and had no issues with them either. I sold that carb (long story) but kept the blocks as they were only a year old and I have them customized for screw in idle feed restrictors. I then today took an air can and sprayed air into the main air bleed and fuel came out my booster just fine for the quick second I shot it with the air. When my truck is running and I take it out and drive and take the air cleaner off everything is dry and no signs of fuel in the main air bleed.

The only time I see this is after it has been sitting and I do not have any fuel boiling issues or anything like that. I am stumped on this one and do not know what could be causing this weird problem. Runs fine, looks fine and the pressure if fine and truck runs just fine in all driving conditions. My carb is a Holley 1850 600 vacuum secondary if that matters.

Anyone ever see something weird like this before? No other air bleeds had any fuel in them.
 

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Check your booster passages for restrictions, if the booster is clogged/restricted it can pull fuel up thru the air bleed, especially if your air cleaner is restrictive or dirty.
 

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Discussion Starter · #3 ·
36 sedan I will check out my booster and see if there is anything in it to restrict it. I never knew that if the booster passages were clogged up that it could cause fuel to be pulled up through the air bleeds. That makes sense to me. I blew out the air bleed and the booster sprayed fuel out very easily and I will keep track on it. If I see it again then I guess at that point I will have to take it apart and blow out the metering block passages and also the check the booster from behind on the main body and see if all is clean. First time for me but makes it odd that only the one bleed would be like that and all the others are fine.

My air cleaner is a K&N style so I need to clean it out and re apply the fluid to it and rule that out but I doubt it is that is it does not look real dirty at all.
 
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