I recently had an issue with fuel starvation of my BETA 20HP engine... the symptom being intermittent running, cutting out randomly and the engine failing to speed up when under throttle. The issue was random and I could find nothing wrong. However, after a few weeks of this I had enough, the lines needed to be checked. A check of the 2x filters revealed nothing amiss. Working back along the fuel pipes I began to find brown waxy 'sludge' in the pipe, and escpecially in the shut-off tap below the fuel tank. I flushed this out - removing a considerable amount of the sludge in the process from the fuel tank. I will now refill the tank (36lt) and add Marine 16 additive to (hopefully) eradicate the problem.

The boat is in the Clyde area of West Scotland, noted for its damp environment. I only use marina diesel which is low sulphur and nil/ low biodiesel content.

Has anyone experieinced a similar issue?

Yes many of us does.

The solution : full tank during winter time (to avoid/reduce water condentation) + additive against bacteries as you said.