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MG MGB Technical - Fuel pump problem

My fuel pump ticks (slowly) even when the carbs are full. I checked for leaks and all seems fine.I tried blocking the fuel pipe to the carbs and it still ticks. Is it an air leak in the pump?
P Hobson

Hob, your fuel pump will always tick just a little even when your float bowls are full.This is normal
James

I thought once the cabs are full the pump shuts off.
P Hobson

I should also have added, the pump ticks when the engine is not running
P Hobson

The fuel pump should be wired to the white wire circuit and therefore should not have power when the car is off. How old are the fuel lines? Leaking fuel lines won't hold pressure.
Kimberly

Have you had your pump serviced in the past?
There are small valves in the inlet and outlet of the pump. If there is some dirt from contamination to the petrol in the tank, they may become leaky, allowing a little flow back to the line, coming from the tank.
Ralph

As Ralph says, if there are no leaks anywhere then it is the inlet valve leaking a little. The Workshop Manual says the pump shouldn't click more than once every 20 secs with the engine stopped, more than this AUF300 type pumps the valve should 'be investigated', on HP pumps either or both of the valve disc or seat can can be lapped like a head valve. In theory the pump can click a lot more frequently than 20 secs and still give adequate fuel delivery, but it is a a warning that you need to monitor the situation and if it starts getting even more frequent then you should do something or risk getting stranded.
Paul Hunt 2

This thread was discussed between 28/08/2006 and 29/08/2006

MG MGB Technical index

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