MG Car Repair: 75 Midget Fuel Leak at Carburator, electric fuel pump, charcoal canister

Question
I am restoring a 75 midget.  Last owner added a separate electric fuel pump switch and it was inadvertently left on.  There was no clicking of pump.  In the morning I heard pump clicking and a huge pool of gas under the car.  The carb throats were wet with fuel.  What could have gone wrong overnight?  The float and valve was working right as the pump cut off after pressure built, the night before.  In the morning, the tank was empty (4 gallons lost).  The dipstick didn't show increased level, so I am assuming that the fuel didn't make it into the crankcase, but will change oil and add oil to cylinders before re-attempting to start.  Any suggestions, please.

Answer
Hi Frederick,
The float needle and seat was not designed to have constant fuel pressure on it over night. You do however need to test fuel pressure to see that the pressure is not too high and over powering the ability of the float to hold the needle closed. I like to see about 1.5 PSI but have seen cars operate ok as high as 3 PSI. (But not hold back the fuel all night) A slightly leaking needle and seat can operate when running as many do.

You are lucky it didn't burn your house down and everyone in it. Check the fuel pressure, put a new needle and seat in and set the float level and check to see that the float chamber venting is clear and the charcoal canister is not clogged up. If it too is saturated with fuel you need to replace it as it is destroyed. Since the tank is vented into the canister too if it is stopped up with fuel the pressure build up in the tank can force fuel into the canister and force fuel past the valves in the pump into the carb too.

Howard