Found informative item on air bubbles in fuel

[Texasgeezer]

Found this early today,

Simple explanation about air bubbles in fuel flow:

https://www.parker.com/literature/Racor/Mobile_Air_Separation_In_Diesel_Fuel.pdf

Appears some bubbling is normal, just needs to be small enough to not cause noticeable engine hesitation.

A slight pressure drop helps bubbles develop. Fuel lines that are marginal or filters in the suction path can help cause bubbles. Those air bubbles do not disappear after the lift pump. Fuel vapor bubbles will disappear after the lift pump.

On the cars that have the small orifice built in the filter housing, it might be a good idea to check that orifice to make sure it is open to allow trapped air out. Might be a reason for engines hesitating now & then.

I'm not suggesting installing the Parker or any other brand of filter. Except for excessive water in fuel I think the Mercedes filter is adequate. Just wanted y'all to know about how air bubbles form in the fuel itself. Other air bubbles can come in when fittings are not good and air is sucked in to join the fuel flow.