Triumph Repair: spitfire fuel pump, quinton hazell, mr gasket

Question
I have a 1978 spitfire mark IV.  it has only 53,000 original miles.  Recently the fuel pump ( I assume the original) died.  I ordered a replacement from an online retailer.  They sent the pump, I bolted it on, and the motor started perfectly, about 15 minutes later it died, I removed the new fuel pump to find the arm broke, about 1" off the top came out separetly from the pump!  I arranged for a return and in the mean time chose to use a Mr. Gasket universal electric pump.   Now here is my problem....I located the new elec. pump on the frame behind the drivers side rear wheel and  replaced the fuel filter in the trunk for god measure.  I was not getting enough fuel pressure at the carb. to keep the motor running, I scarcely had any fuel flow at all.  first i tried replacing the entire line with 5/16" rubber line, that did not help.  i then used 1/4" line, this improved the situation but the engine still will not run for any more than 4-5 minutes.  Do I need a pressure regulator or some other type of elec. pump?  Is there another mech. pump (other than the Quinton Hazell that I have already seen fail) available?

Answer
this is one i need some time on. i'm not familer with the pump you have put on. i might get a gas can about a gallon or so and run the pump with a filter sitting next to the engine and hooked up to the carb. this eleminats the gas tank which might be rusted or have a blocked vent line. try this test and let me know what happens. this also sounds sort of like a electronic iginition problem. Dave