I need a really good carb guy!!

[my89notchback]

So my son and I fired the mustang back up for the first time since the fuel system mess. Everything is new except for the carb. It’s an AED 950HO race carb. It’s all clean and runs fine until the fuel pump is turned on. Float levels were both set, needle and seat were nice and loose front and rear, but fuel shoots from the vent tubes!!

Help!!

 

[AutoRoc]

6-7psi?

 

[my89notchback]

6-7 psi. New Magnafuel regulators. Do I need to change out the needle and seat? What else could it be?

 

[AutoRoc]

Are you sure it has the carburetor (low PSI) spring inside the regulators? is it possible that has tight Springs in it for EFI but you turned the pressure all the way down to 6 PSI? I did this with my Aeromotive and it caused all sorts of weird things to happen.

 

[camaromann]

Did you set the float level with the engine and fuel pump running?

 

[my89notchback]

Are you sure it has the carburetor (low PSI) spring inside the regulators? is it possible that has tight Springs in it for EFI but you turned the pressure all the way down to 6 PSI? I did this with my Aeromotive and it caused all sorts of weird things to happen.

Yep. It has the correct spring.

 

[my89notchback]

Did you set the float level with the engine and fuel pump running?

Floats were pre-set for start up and then reset. As soon as the pump turns on, the fountain starts.

 

[camaromann]

Well the only thing I can think, is maybe turn the float way way down and then raise as the engine and pump are on. Do you know what that fuel pump puts out psi wise? You might need to turn the pump itself down instead of the regulator. It might be more psi then the regulator can handle. Its obviously doing 1 of 2 things. Either floats are just set too high, or the pump is pushing through the region and then pushing past the needle/seat/float. Without being there it's hard to guess online.

 

[DarkoStoj]

Get this book, then you will know exactly what to do in every situation regarding a carburetor. Its awesome. https://www.amazon.com/Vizards-Modi...d=1539621715&sr=8-1&keywords=holley+carb+book

 

[fatblock]

The needle and seat outer o-rings may not be sealing on the bores.Pull them out and inspect everything again.You may have to lightly polish where the seal rides.They do tend to pit a little in this area.Good luck.

 

[Detroit Gearbox]

Needle & seat are bad.... pressure is high.

 

[my89notchback]

The needle and seat outer o-rings may not be sealing on the bores.Pull them out and inspect everything again.You may have to lightly polish where the seal rides.They do tend to pit a little in this area.Good luck.

It was the rings not sealing on the needle and seat! I did an air test at 6psi and the were hissing. Put the new ones in tonight and fired up with no fountains.

Thanks!!