Avoiding air in diesel fuel lines ?

[Robin2]

I have a 90 litre plastic fuel tank (Plastimo) which has no baffles in it. I suspect that there is a risk of the fuel lines drawing in air when the fuel sloshes around as the tank empties. If that happens I presume the engine (Yanmar 1GM) will stop as soon as the air reaches the injection pump.

Does anyone have any suggestions about how to avoid / eliminate the problem - short of replacing the tank?

I don't think it is practical to fit baffles into it but maybe someone has done so.

 

[Guest]

Hi, My immediate thought is
, if you have room, to steeply favour the outlet end of your tank ie arrange it so the other end (hopefully the filler end) is significantly above the fuel line end this should create a sort of baffle by confining the fuel over the outlet and it should be less affected by the motion of the boat. Hope this makes sense to you
Best regards, Bert

 

[aztec]

is the fuel tank designed for the installation. ie does it have return lines for the spill off etc. if so the small amount of air should pass throught the lift pump without air locking the system, the criteria being the fuel level. hope this helps.

 

[Robin2]

The return fuel line comes from the injector pump, not the lift pump so I presume the injector pump will air-lock before the air finds its way back to the tank.

In answer to Bert, I don't have room to incline the tank. It is level.

 

[Guest]

Robin, Aztec is correct. Dont worry that the return pipe comes from your injector pump. Thats where it's supposed to come from. The lift pump supplies more diesel than the injector pump can handle, the remainder is blown back to the tank. Although you say that the diesel is sloshing around the chances are that its not actually drying the bottom of the tank outlet.

 

[Trevor_swfyc]

If air is being drawn off, then I would fit a small secondary tank at a lower level with a breather return to the main tank. Take the supply from the secondary tank at its low point this would completely eliminate the problem.
Well I think it would!
Trevor.