Lucas 10efi negative atmosphere in the gas tank problem

[burlbark]

 The other day I was running and got finished with a  two logs (600 bd feet) and I noticed that the gas tank was nearly half its volume. It appeared that the breather system is plugged. Does anyone know how this system works on the 10efi?

I opened the cap and the tank expanded out and is about back to normal but I would like to make sure I dont let something get worse. Anyone familiar with this model out there?

[sigidi]

I've been running my 10" EFI for around 280hours haven't had any trouble with the fuel tank pressurising. How many hours has yours done? Service at 200 hours replaced the EFI filter with the original part?

I'm not sure why it is specific, but maybe if not using the genuine part it may lead to this? Just speculation...

[mad murdock]

I have not seen a Lucas up close, but if it has a standard plastic fuel tank, and no vapor line going to the engine intake plenum, I would venture a guess that the fuel cap should be a venting type cap, and is not working properly. A new fuel cap if that were the case, would fix the issue.