Bleeding curiosity...

[Phototropic]

So today I serviced the fuel system on my boat for the first time so I now stink of diesel. During the bleeding process I was confused as I have a fuel tank above the level of my cav per filter which then feeds int my Yanmar 1gm fuel lift pump and then the primary yanmar fuel filter....what confused me is after removing and changing both filters I put them back together and reopened fuel from the tank then opened the bleed bolt on the cav...now for a while it bubbled but then it starting raining diesel and yet the glass bowl etc below was empty of diesel? It didn't seem to want to fill until I started pumping the lift pump and opened the bleed screw on the primary yanmar fuel filter. Now I would have thought the cav filter would self prime due to gravity from fuel tank...am I missing something? Or was it a result of the further air gaps beyond in the yanmar fuel filter? Would be good to know for the future.

After three attempts at bleeding I got the engine running nicely and was rather pleased its myself.

 

[TQA]

Wear latex or nitrile gloves.

Yes I would have thought you should get fuel flow from anything lower than the tank.

 

[pvb]

...then opened the bleed bolt on the cav...now for a while it bubbled but then it starting raining diesel and yet the glass bowl etc below was empty of diesel?

There was no outlet for the CAV filter, so it just overflowed. If you'd opened the bleed on the engine filter, fuel might have run through under gravity. In many installations, it's not necessary to touch the bleed screw on the CAV filter.

 

[Lakesailor]

You had a volume of air downline of the CAV filter. Until you open the lower bleed it will prevent further movement of fuel downline.