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Discussion Starter · #1 ·
Engine seems to be running fine with no bog or drivability issues but I have fuel coming from passenger side primary booster while idling in the driveway starting at 2k rpm and up. Check out this video. Is this normal?

 

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Discussion Starter · #3 ·
No, that isn't normal. Check pressure and or float level.
Pressure is high at 8.5 but it's a Carter 172 that is advertised at 8.5 psi. Many people have run without a regulator here on TC. It was a real popular pump about ten years ago. I took the site plug out and ran engine to 3k without any fuel spilling out.
 

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Pressure is high at 8.5 but it's a Carter 172 that is advertised at 8.5 psi. Many people have run without a regulator here on TC. It was a real popular pump about ten years ago. I took the site plug out and ran engine to 3k without any fuel spilling out.
Well that would eliminate those 2 possibilities or definitely on the float level . Wouldn't hurt to try running 7 psi to see what happens though. Then if that doesn't fix it then go through it as mentioned
 

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Discussion Starter · #6 ·
Get yourself a carb kit and go through it. Something is plugged and or out of adjustment. Plugs are probably black.
I've already put a kit in it. Guess I'll have to do a second kit and blow it out real good.
 

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They are advertised no regulator needed. Mine flutters between 7 and 8ish also
Wonder if turning it down a hair would help.
If one used 6 lbs and it put out 8 is the extra 2 lbs gonna damage the pump or shorten its life?
Is a return needed?
Keep us posted OP. Do like the pump doesnt seem to run out of fuel
Sucks they discontinued it and we are forced to spend hundreds to buy Holleys replacement

If a new one is spotted online Im buying it!
 

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Discussion Starter · #9 ·
I’m guessing that the main metering air bleed is blocked. Get some carb cleaner with the little plastic tube and blow it out. It’s the one towards the middle of the carb.
Okay thanks, I'll give it shot.
 

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Discussion Starter · #11 ·
In addition to above suggestions, you might want to pull the needle and seat out to see if a piece of trash got hung up in there causing a flood condition.
I had the sight plug out during part of my testing. Floats held their adjustment, but it couldn't hurt while I have it apart.
 
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If fuel is getting to one primary booster and not the other I can not see any possibility. that float level or pressure could be the cause.
Fuel travels through the primary jet, up through the emulsion tube in the metering plate and into the booster. There has to be a restriction in that pathway and/or one of the air bleeds for that venturi as mentioned in a prior post.
 

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Since the fuel is only coming from one booster I would look at the metering block and kill bleed holes to see if ones plugged, looks like that booster is siphoning fuel some place. If it were a float or the fuel level were too high both booster should do that. Set the float level lower first and see if that helps. I run no more than 6 psi on any Holley.
 

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Discussion Starter · #14 ·
If fuel is getting to one primary booster and not the other I can not see any possibility. that float level or pressure could be the cause.
Fuel travels through the primary jet, up through the emulsion tube in the metering plate and into the booster. There has to be a restriction in that pathway and/or one of the air bleeds for that venturi as mentioned in a prior post.

Thanks for reaffirming all of the above. This will be third time blowing through these passages but this time I'm going to use compressed air so I can listen for whistling and compare the two circuits.
 

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Discussion Starter · #15 ·
Since the fuel is only coming from one booster I would look at the metering block and kill bleed holes to see if ones plugged, looks like that booster is siphoning fuel some place. If it were a float or the fuel level were too high both booster should do that. Set the float level lower first and see if that helps. I run no more than 6 psi on any Holley.
I already have both floats a tad low, but I guess it wouldn't hurt. I'm going to take it apart this morning. I've already cleaned it with brake clean twice but this time I'm going to use compressed air so I can listen for a restriction.
 

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Use carb cleaner. Brake clean is different. Protect painted surfaces. If you are not concerned about having a pretty carb, you can get cleaner in gallon cans and let parts soak overnight.
2000 rpm is off the idle circuit. Focus on the main circuit as mentioned above. Look at the gasket impressions on the meetering plate and follow the flow of air and fuel.
You probably just sucked some debris from the tank and it is stuck in the small internal passage.
What filters do you use?
 

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Discussion Starter · #17 ·
Use carb cleaner. Brake clean is different. Protect painted surfaces. If you are not concerned about having a pretty carb, you can get cleaner in gallon cans and let parts soak overnight.
2000 rpm is off the idle circuit. Focus on the main circuit as mentioned above. Look at the gasket impressions on the meetering plate and follow the flow of air and fuel.
You probably just sucked some debris from the tank and it is stuck in the small internal passage.
What filters do you use?
I have it apart at the moment. I've been reading up on Holley's and I'm pretty sure I can identify all the circuits. I can't detect any difference between the right and left side as far as carb cleaner spray restriction or with compressed air. Focusing on the high speed air bleed and main well including the throttle body. I'm not sure if this thing will come clean. Maybe it's in the emulsion tube or some other difficult spot. I was pretty thorough on the rebuild and this is my fourth time blowing out the passages. I might need a new metering block. I'm going to blow it out some more and see what happens. I'm not feeling optimistic.

This was one of the most difficult rebuilds I've done. When I first rebuilt it months ago. It's an older carb that had the factory gaskets and they don't sell the Permatex gasket remover anymore. Chem-dip isn't what it used to be either. I thought it would be a miracle if it would run. Surprisingly it kept much of the factory finish and everything else seems to be in great shape. The engine actually runs good except for running rich. So I'd like to make it work.
 

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Discussion Starter · #19 ·
Are all the air bleeds clean on that booster that's dropping extra fuel?
Yes they are. I cleaned everything out several times and put the carb back on. I ran out of time so I'll start it in the morning. I didnt find anything clogged so I'm not optimistic.
 
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