Loss of power at high revs

[Gasy]

Last week had loss of power at above 3000rpm and white smoke
So just changed diesel filter
Ran a lot better but not right at high revs
So just cleaned out banjo filter thing runs well now revs are back up to over 4000rpm with foot to floor before it changes gear
Guess the veg oil has shifted some muck
But I have a hiss / suction noise when I open fuel filler cap
Is this normal or do I need to clean filler cap
Cheers and thanks

[Simon Jones]

A bit of vacuum when removing filler cap seems normal on a diesel. On the V6, it seems to be the opposite way round with positive pressure escaping. Possibly due to the petrol being pumped from the tank rather than drawn by injection pump with the diesel.

[Northern Bongolow]

look on this link, there is a vent pipe back up to the filler neck to tank, then a one way valve from tank top to the inner chassis rail, both of these can get blocked.
the filler neck pipe gets filled with road crud, blow it out, not in. the tank breather which is clipped to the inner edge of the rear chassis rail, just clip it off and blow it clear, they are usually stuck shut with over enthusiastic undersealers crud.

if you remove the pipe from the tank to the fuel filter and blow back (deep breath needed) you can clean the tank pickup filter, this makes a heck of a difference.

http://lushprojects.com/bongopartsmk2/c ... mgno=.html

[Gasy]

Have done the blowing down into tank to clear pick up filter
Will try the vent tomorrow
Cheers