Classic/Antique Car Repair: fuel pump 1960 healey 3000, diaphragm spring, electro magnet

Question
just started: when key is turned on fuel pump races fast and wil not shut off or slow down, even when car is running.

Answer
Hi Art,
If it is an SU pump you have several possibles.

Air in the fuel line or pump.
Fuel pump contact points out of adjustment
Pump diaphragm ruptured
fuel leak or carb float problem
Or simply running out of fuel to the pump.

The pump has an electro magnet that pulls a diaphragm that is spring loaded. The diaphragm has a long pin attached that operates the contact points so as to disconnect the magnet which allows the diaphragm spring to push fuel toward the carbs via a one-way valve. As the spring pushes the diaphragm and fuel, the pin allows the points to close again which in turn allows more fuel to enter the pump via a second one-way valve. Once fuel pressure is built up on the carbs side, the spring can not push any more fuel so it will not allow the pin to reconnect the points, thus the pump stops clicking. When a SU pump continues to click rapidly one or more of the above things is wrong.
If this came to me in my shop, I would first check to see that a good supply of fuel was getting to the pump. Then I would block off fuel coming out of the pump and turn it on to see if the pump stopped. If it does the problem is further forward. If it still ran fast then the pump is at fault and should be disasembled and corrected.
I hope this helps.
HMF