Morris Minor Owners Club

I have recnetly fitted another pump to my morris as old one was leaking at diaphragm - ever since the leak now come from top of float chamber - I have tried 3 other floats and valves - each tested in water and also by blowing through and operating valve and itsa still happening - so is there a cut of valve in the pump which may be sticking - i guess there is otherwise pressure would build up in the pipe??? if there is such a valve how can i access it and unstick it - the pump in a NOS item which looks excatly the same as original in dimensions and is genuine factory rebuild. Is it possible this has a different output than my original pump? any help or tips gratefully recieved as i am at the end of a 15yr rebuild and hhope to debut at a show in just 1 1/2 weeks!

If the leak is coming from the top of the float chamber where the top fits on the fuel bowl, then the needle valve is not cutting the fuel off properly.

Check that you have not got a hole in the plastic float, as this sometimes can get filled with fuel and not shut the valve off properly.

Other than that, it is either the needle valve not operating (can be tested by the blow through test as you mentioned) or the fuel pump is supplying too much pressure, which I would say is unlikely.

Try connecting the fuel hose to the removed fuel bowl top and check it's operation over a bowl or bucket just to verify that it is not the pump that is producing too much pressure, although I suspect it might be the float.

As Cam says, if the leak is coming from the very top of the float
chamber(from behind where the little inlet pipe protrudes) then
the float needle and seating is faulty. Don't forget that the more
the pressure from the pump the more the needle will be pressed
into its seating so it should be self regulating when working correctly.
If the leak is from the gasket on the lid of the float chamber then
your float cut off height would appear to be wrongly set??? in my
experience the float needle always fails when the car has been
laid up for a rebuild, either straight away or after a couple of
hundred miles back on the road.

As Cam says, if the leak is coming from the very top of the float
chamber(from behind where the little inlet pipe protrudes) then
the float needle and seating is faulty. Don't forget that the more
the pressure from the pump the more the needle will be pressed
into its seating so it should be self regulating when working correctly.
If the leak is from the gasket on the lid of the float chamber then
your float cut off height would appear to be wrongly set??? in my
experience the float needle always fails when the car has been
laid up for a rebuild, either straight away or after a couple of
hundred miles back on the road. Then again you have tried
different valves etc so I wonder if you have the correct pump??
there are pushers and pullers( the MGB's and Midgets were pusher
pumps) the Minor is a 'puller' double check the type.