Leaky Weber pump jet question

911mnypt · 02-08-2012, 08:05 PM

After a fairly long drive I parked Ruby in the garage and smelled fuel from the right bank of carbs. Pulled the covers off and one of the pump jets was still flowing fuel at a good pace. Messed up ball-bearing in the delivery valve?

Thanks,
Richard

1QuickS · 02-08-2012, 08:26 PM

Are you saying that with the engine stopped and the electrical system switched off that fuel was coming out of one of the squirter nozzles that is located above the main venturis?

There are three distinct flow controls in the accelerator pump system; two are closed when the throttle pedal is stationary and the other is open. The two that are closed consist of the check valve that is integral to the bolt that secures the squirter nozzle to the throttle body and it keeps fuel from flowing back into the fuel bowl via a gravity-closed ball bearing. The other closed flow control is within the pump body and consists of a disc which is pressed by a compression spring and acts against a rubber diaphragm that seals the three fuel delivery galleries to the squirters. The last check valve is the fuel inlet valve in the rear fuel bowls and it closes when the accelerator pedal is depressed.

Since the squirters are above any fuel source in the car the natural tendency is for fuel to drain into the fuel bowls if the check valve (bolt) and the rubber diaphragm are defective.

A curious problem if I understand the symptoms correctly. Also curious that the fuel continued to flow long enough to get the top of the air cleaner off and view the issue.

If fuel is draining from the auxiliary venturi or from the progression port holes then these are understandable.

911mnypt · 02-08-2012, 08:44 PM

Hi Paul...yes, engine off and electrical shut down, one of the pump jets still weeps fuel, enough for me to smell it and feel it with my finger.

1QuickS · 02-08-2012, 08:59 PM

It could be fuel in the gallery is expanding by heat-soaking after shut-down and coming out. Higher chance of this from the longer fuel galleries such as for cylinders 1, 3, 4 or 6. I would think that you would have suffered fuel bowl percolation issues first which is what you smelled. Maybe you did and by the time you got the top cover off you saw only the fuel coming out the squirter. Did you see fuel around the throttle shafts, in the bottom of the air cleaner or on the engine shroud? Do your top covers have the bypass holes drilled into them? Do you have insulators between the heads and the intake manifolds?