79 t-bird driving problem

My 79 t-bird has a 351m engine and a FMX transmission and every once in a while when I accelerate I hear a small tick and the whole car jolts back and then keeps driving like normal.At first I thought I was running out of gas but it did it after I filled it up.I have had to replace the fuel pump before, could it be defective or could it be the engine?
 
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