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MG TD TF 1500 - fuel pump ticking when running

Hello,
My newly rebuild SU fuel pump ticks very slowly when ignition is switched on, and once carbs bowl are full. Tens of seconds. But it ticks very rapidly when the engine is running. several times per second and irregular.
The car drives with no problem. But I cannot hear the pump rythm.

I'm thinking of vibration because there is no spring on the disk valves.
Could new rubber mounts solve the problem ?

Laurent.
LC Laurent31

Laurent
Have you mounted the pump correctly with the outlet at the top
William Revit

You may have a float in the carb that is not allowing the needle and seat to fully seal when the float is up. It should stop the flow of fuel, causing the pump to stop ticking when the carb bowls are full. Especially when the engine is not running.

.. CR
CR Tyrell

yes william : outlet at the top.
precision : carbs are not overflowing so I think that the diaphragm is pushing fuel back through the inlet valve.
LC Laurent31

Laurent,

This problem could be caused by an air leak on the input side of the pump. The way to test for a leak is to unscrew the fuel pipe from the rear carb and put the open end in a bottle, switch on the ignition and look for bubbles in the flow. Has a filter been added before the pump? If so you should remove it.

John
J Scragg

John, it ticks very slowly when the engine is stopped.
So there would be a leak only when it runs ?

Laurent.
LC Laurent31

Basic question. Have you done a flow test on the pump into a bucket to assess if it is pumping within tolerances? Check the WSM for the flow rate. They have an elaborate test mechanism but you could probably approximate something close.
Christopher Couper

This thread was discussed between 09/06/2020 and 12/06/2020

MG TD TF 1500 index

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