Fuel tank venting issues, 3.9 EFI in my 90, any ideas please...

Evening all,
Quick question and easily answered by someone im hoping!
I have recently fitted a 3.9EFI into my 90, all is going well, i found originally that the fuel tank was building up pressure so i tee'd a pipe off the small pipe that comes off the side of the filler neck and that sorted the problem, but has caused another. When on a steep upward incline while off-road it now has taken to siphoning the contents of the tank until i level out .

the tank is a std 200tdi with a RRC in tank pump fitted.

any help will be gratefully received,

thanks Gareth

Have you got the return from the injection rail plumbed in?
Is the fuel cap a vented one and clear(vents though the key hole)

Hi vougese39, I have the return plumbed in, It has a standard 200 tdi fuel cap, is there any easy way of testing if the cap is venting?

Hi Geb I am not sure if this is any help?. But I have a 3.9.disco and when ever I remove
the petrol filler cap there is ALWAYS a loud hiss while the air escapes,it still works ok
perhaps its normal.

you need to extend the breather tube much higher so it wont even start to syphon. on my petrol v8 rrc this hose goes right up to the black viynl on the rar quarters!

Thanks Fett, that's just about what I have ended up doing. Coming up the roll cage and returning to just lower than the tank.

To check the cap is venting suck and blow though the key hole old trick and the best