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General Tech Using Fuel Pump Lever When Setting SU Floats

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KVH

KVH

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When adjusting my floats I’m having an issue on the front, leading carburetor. I installed a new seat and Viton tipped needle. I set the gap to lid at about 3/16. I filled the bowls using the manual pump lever. I had fuel running out of the jet into the intake manifold. Clearly not right. I’ve tried two even larger gaps, 1/4 and 5/16. Same thing. The level in the jet is too high, spilling from the top. I checked by removing that piston of course.

I’ve checked the needle and seat out of the car. It closes and seals properly.

Is the problem likely that I’m using the manual lever to refill the bowls? Does the manual lever push too much pressure into the line and cause a bypass of the needle?

PS. I have HS6 carburetors on my vehicle.
 
Shot in the dark: Is your float compromised?
 
The correct adjustment for TR3 and TR4 SU floats is established by using a 7/16-inch diameter rod (I use a drill bit).

Any excess fuel should run out the float bowel overflow tubes, not the jets.

On both the original and the aftermarket fuel pumps for my TR3a, the priming lever appears to stop working at some point; meaning I stop feeling that moving the lever is doing anything.
Maybe this is because it feels a resistance when the float bowels are full and the needle and seat are closed. I don't really know.
But once I feel it is no longer pumping, I just start the car and go on my way.

Have you tried starting the car to see how it runs
 
My float is also new. I’ve checked it and see no evidence of cracks or leaks. That 7/16 spec for the lid gap is actually for a different model SU, usually the one with the brass fork closing lever under the lid. It’s shown in the SU instructions, but that’s not for HS 6 carbs. The instructions for HS 6 is 1/8 inch, but the SU website says you can increase to 3/16 inch.

I think I need to experiment running the engine to fill the bowls, rather than using the pump lever. That means I can’t verify or check fuel level in the jet without dismantling the carb housings each time. A bit of a hassle but, oh well.
 
When the pressure comes to spec (about 3 psi), the fuel pump lever should not pump any more. It goes "limp". It does sound like maybe your pump is overpowering the float. If you have an old vacuum gage, it also has a fuel pressure side to it...so it can be used to test your pressure is below 3psi.

All above are also correct...if your float has a leak it will not float, and therefore will not close the valve.
 
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