bison
Well-Known Member
Tank vaccuum will become exessive if the cap is plugged(my cap happens to be solid plugged) which can in worse case scenario cause a collapsed tank.
It is also equally hard on the LP and IP cause less fuel to the IP means less IP cooling and less fuel for the engine.
I prefer no tank vacuum at all and to circumvent any vac problem i always left the cap loose but i found that while driving the cap seated itself back on the neck over time and as the tanks level got lower the fuel pressure got lower also till in the end it was 0.
There was 3-4 PSI fuel pressure diff in having vacuum or not.
Yesterday after the umtied episode with vacuum forming again i decided to take the cap apart and have a looky see wat's ailing.
The white insert is held in place by 4 tabs in the black lid and can be taken out by careful prying with a thinbladed screwdriver between the insert and the tab and lifting the insert up to clear one tab and stick a piece of wire trough the slot under it to keep it from snapping back before prying the next tab.
Once you got the insert out you''ll find there is a screen on the backside of the insert,..in my case it was solid plugged with dirt.
After cleaning the screen and pressing the insert back in the lid the cap should be back to new.
If you like me don't want any vac in the tank,you can take the little valve(tankside) out of the insert by breaking out the slotted circle in the centre and removing the spring and valve.
Now i can crank the cap down and never have to worry about vacuum again.
Some pics before and after.
It is also equally hard on the LP and IP cause less fuel to the IP means less IP cooling and less fuel for the engine.
I prefer no tank vacuum at all and to circumvent any vac problem i always left the cap loose but i found that while driving the cap seated itself back on the neck over time and as the tanks level got lower the fuel pressure got lower also till in the end it was 0.
There was 3-4 PSI fuel pressure diff in having vacuum or not.
Yesterday after the umtied episode with vacuum forming again i decided to take the cap apart and have a looky see wat's ailing.
The white insert is held in place by 4 tabs in the black lid and can be taken out by careful prying with a thinbladed screwdriver between the insert and the tab and lifting the insert up to clear one tab and stick a piece of wire trough the slot under it to keep it from snapping back before prying the next tab.
Once you got the insert out you''ll find there is a screen on the backside of the insert,..in my case it was solid plugged with dirt.
After cleaning the screen and pressing the insert back in the lid the cap should be back to new.
If you like me don't want any vac in the tank,you can take the little valve(tankside) out of the insert by breaking out the slotted circle in the centre and removing the spring and valve.
Now i can crank the cap down and never have to worry about vacuum again.
Some pics before and after.