Yesterday I replaced the fuel filter, unfortunately the car is still the same. however i came across this (the grey fitting in the fuel supply line)


I've taken it off and replaced with a new fuel hose. Its a one way check valve. the engine bay of the car is covered in red dust except for that so it must have been added recently. any ideas why? Worn IP pump?

I'm not able to do the comp test for a week as im waiting for the adaptor thats coming by post from over east. Any suggestions of what I could try and check till then?
Thx