Fuel pressure creep

[zeroracing]

I am having the following issue. After shutting off the motor I get a residual fuel pressure pushing fuel into the bowls...

Have a cv billet pump, Allstar regulator, and KB carb (no return line). After shut off the fuel pressure needle drops very very slow, going from 6 psi to 0 in about 20 seconds. At the same time you can see the fuel bowl level creep up in the sight glass.

Anybody else have this issue? This is a new system for me and runs great, I will note they are used parts, is it normal for the cv pump, a regulator issue?

Like I said runs great and constant 6 psi...

[Brian Gray]

Doesn't sound like a problem your just bleeding off residual pressure because of the regulator. Ran the CV pumps for years top the line stuff. If you don't need the regulator though I'd get rid of it.

[let-r-eat]

Regulator on front of fuel log?

[zeroracing]

Yes regulator on front, the cv pump is a little much without the regulator.

[Brian Gray]

The reason I asked if you need it 7.5 to 9 should be about what the pump is set for. On gas that's ideal to me I wouldn't want a regulator messing with my fuel flow. Not a big deal until your on a big wide open track.

[lmdriver72]

I would replace the needle and seat in the carburetor nothing should be getting past them to have the fuel level rise it could be the o ring or the needle and seat itself. I've had both go bad and they got so bad it would finally flood just while idling.

[let-r-eat]

I've seen many times with aftermarket carbs the needle and seats they use don't like 6.5+ pound. The original Holley needle and seat is the best there is. I would find a couple. Is the level increasing in both the secondary and the primary?

[dirtracerl77]

If you mount the regulator after the carburetor it will never mess with fuel flow. That is the way regulators are intended to work. They keep pressure constant in front of them and bleed any access off to the tank. This also allows you to keep pressure on the lower side of the scale to keep needles from bleeding over. I never run more than 6psi. It stays constant from idle to top RPM.

[Lizardracing]

Is this a dead head regulator?

Don't equate pressure with flow. They are not the same thing. Pressure is flow with a restriction so increasing the restriction will reduce the flow. You can increase the flow without increasing the restriction to but then you get into pressures the needle/seats can't handle at a reduce flow rate. Regulators typically flow more with less pressure because the orifice is bigger. 5/6psi is plenty. On Alky, the needle/seats are physically bigger for the added flow and Alky has a different buoyancy factor and so they have different pressure requirements. It's poor practice to increase restriction to get the perceived pressure rate. We use pressure as a way to monitor flow rates rather than flow meters because flow meters are more costly and harder to calibrate and mount. That being said I don't believe anyone makes better needle/seats than genuine Holley Stuff. I'd recommend two new ones a two spares and likely never worry about it again. I've never liked the cheesy lock nuts that come in several off brands rebuilder kits either.