I'm having a rather odd problem with my 1989 Fourtrak 2.8 turbo diesel. If I park it facing uphill then no matter how hard I try, I cannot start it. Pumping the priming pump (after opening the bleed valve) doesn't lift any fuel up and the only way I have got round it is by disconnecting the fuel inlet line to the left of the fuel priming pump/filter and releasing what I presume is an airlock. I can then lift fuel and away she goes. I thought these things had a sealed fuel system so I can only assume that somewhere I have got a leak but I can't find one for the life of me.