Volvo Repair: keeps cutting off, fuel pump relay, relay switch

Question
I just bought a 1989 Volvo 740gl it sat up for about 1 year. After buying it it ran very well the first 1000 miles i then added fuel injector cleaner and thats when trouble started. I changed the fuel pump under driver seat this was a problem from the start says the owner i also changed the filter now when i start the car it will run and you can hear the pump making a whinng sound then cuts off. It runs for made 5 mins or ten miles. Once it cuts off you can start it right up again. do you think its the pump in the tank or the relay switch or something else.

Answer
I would have the pump in the tank checked and the hose that is in the tank attached to the pump.then I would replace the fuel pump relay especially if it is the original which you can tell by the numbers on it it will have the year day month on it.

Rege