fuel problem?

I have recently purchased an H Reg Volvo 940 GLi lambdasond
I thought the people i was buying the car off were being generous when they sold the car to me with over half a tank of petrol in it.
Well like a new toy i was busy driving the car on little trips. On returning i stopped the car, went for a coffee and when i went out to the car i tried to start it. It would turn over no bother but not burst into life. After a bit of elimination and even thought the gauge was telling me I had a quarter of a tank of fuel, when i put a gallon of petrol into the car it sparked into life. Evertime the level drops to aroung a quarter tank full the car splutters and needs me to fill it up. Is there a pipe or something that gets dislodged on the fuel pump in the tank, I presume that is where the fuel pump is?
Any help would be greatfully received:-)

[Peter Milnes]

The fault is indeed a split piece of pipe in the fuel tank. You will need to remove the whole assembly from the tank and probably replace the pipe and the sock as well. Assuming that there is also no fault with the in-tank pump that is.

All the best, Peter.

Thank you very much for the reply Peter , I will now have a look and see if I can repair it
thanks again:7