Nick

[Nick]

I have spitfire 1500 .  We have a problem with fuel leaking from one of the carburettors . My mechanic fitted a new fuel pump =. Is that the issue

[Steve P]

Could be,some modern repro pumps put out too much pressure for the float valves,worth cleaning and checking the valves first,check for debris or slivers of fuel pipe floating around.

Steve

[johny]

Hi Nick, this seems to be quite a common problem and is definitely connected with the replacement pump. The new pump could just produce more pressure because its new (new internal spring) and then, because the float valves might not be at their best, the increased pressure overcomes one when it closes. The other possibility is that as Steve says the repro spring might not be the same specification as the original so increasing the output pressure and even good valves might struggle to shut off the flow.

Apart from cleaning as suggested theres two further options: overhaul and use the original pump so you get less pressure or replace the float valves and hope they will be good enough to do the job correctly. Obviously measuring the fuel pressure, if possible, would be very useful....   

[Adrian]

My GT6 suffered from fuel starvation until I replaced the pump. So far so good but was aware that they can over fuel the carbs so maybe it depends on supplier / batches. Fall back was a rebuild.

[Pete Lewis]

disturbing any fuel hoses can make the dreaded rubber slivers  these little sods get cut off when you fit hose to metal tube   they float about in the supply 

and get jammed in the back of the float needle valves 

easy to check on SU more difficult on Strombergs  , 

a good squirt into a jar afet any work is a way to catch some 

Pete