MG Car Repair: 1971 MGB GT Fuel Pump, screw holes, float bowls

Question
Howard

Thanks for your help in the past.  You've been spot on so I'm going back to the well one more time.  

I have a 1971 MGB GT.  The fuel pump was leaking within the body but was still operating correctly.  I had a new diaphram and installed it according to the instructions.  I did not replace the points.  (I do have a new set but have not installed them yet) The pump runs and does not leak.  

I've owned many MGB's over the years but I need your opinion.  I know when you first turn on the key, you will usually hear a slow click...click...click... while the pump fills the carb float bowls and then it will stop.  My question is, how fast should that clicking be once the engine starts?  Should it still be that same slow click...click...click or will it speed up?  When my car is running, the fuel pump is clicking very quickly at probably 5 clicks per second or so.  Is this normal?  

When I installed the diaphram, I followed the instructions exactly as far as how many turns to adjust the screw and the back it off.  I'm wondering if I've adjusted the stroke on the pump to be too short and therefore the pump is running too fast and supplying less fuel per stroke of the diaphram.

Maybe I'm being paranoid but I don't want to burn up my pump at some inconvenient time.  LOL  Do you know how fast the pump should run when the car is running?

Thanks again.

Dave  

Answer
Hi Dave,
I think your concerns are correct. Either the stroke is too short or you have a pump valve leaking. As long as the carburetors are not flooding and there is no fuel leak or air leak between the pump and the tank

I would examine the pump valves and readjust the stroke. Try this, screw the diaphragm in and keep pushing in on the center of the diaphragm to make the point rocker flip over until when you push it in, it no longer flips. Then back the diaphragm out 4 screw holes and try that. You can experiment with a different number of holes.

Normally the pump will click rapidly until it fills the float chambers and then slow to a stop and only click occasionally. When the engine is started and running the clicks will represent how much fuel is used but 4 clicks per sec is much too fast. When I hear that, I look under the car for a fuel leak or a flooding carburetor or a air leak between the pump and the tank.

Howard