Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

throttle plate v.tubes filled

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F250 Restorer:
I can't seem to get any flow to my secondaries. I checked and ran a thin copper wire through the four tubes. The innner two are bleeds that vent through the airhorn. The outter two exit through a hole in the air horn. I thought those were the supply to the secondaries discharge tubes, but no. So, how do the secondaries get fuel?

Thanks.

Kenth:
Fuel flows thru the metering discs in bottom of the float bowl were the secondary rods sits and up the channel were the secondary main well air bleed tubes (the small inner tubes in air horn) sits and out of the main discharge nozzles.
The larger (outer) tubes i air horn are the accelerator tubes that pull fuel out of the holes in front of the air valves when they opens to cover for the incoming air before the main discharge nozzles comes in. This pull over enrichment system acts much like a secondary acc pump.

HTH

F250 Restorer:

--- Quote from: Kenth on September 26, 2020, 02:05:00 PM ---Fuel flows thru the metering discs in bottom of the float bowl were the secondary rods sits and up the channel were the secondary main well air bleed tubes (the small inner tubes in air horn) sits and out of the main discharge nozzles.
The larger (outer) tubes i air horn are the accelerator tubes that pull fuel out of the holes in front of the air valves when they opens to cover for the incoming air before the main discharge nozzles comes in. This pull over enrichment system acts much like a secondary acc pump.

HTH

--- End quote ---

Thanks for the explanation. So, when I look up the discharge tube, I can see that the inner tubes meet the top of the airhorn. Shouldn't there be a gap so that fuel can be pulled out? And if so, how do drop them down a bit? Thanks again.

Kenth:
The smaller tubes adds air to the mixture and are smaller than the channels for the fuel to pass.

F250 Restorer:
Thanks again.

I think I got it, ha ha. Fuel is pulled in when secondary rods are lifted. That fuel passes the bottom of the inner tubes and air is then added as it is pulled past. It travels up the outer tubes and across the airhorn to the discharge tubes. Why is there a hole in that passage, in the airhorn, between the top of each outer tube and the discharge tubes? Each hole sits above each air flap. That has to be like an acc. pump squirt as the air flaps open, right?

I can't get air past those holes to the discharge tubes. If I plug each hole and blow through each outer tube, I got nothing coming out the discharge tubes.

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