Hi.

You can follow the diagnoses algoritmh on http://www.recarbco.com/technical/newtrouble.html, it works for me on a similar situation.

Also, I suggest to put two fuel filters: one before the pump (universal type) and other (usually a bit smaller - I use a cheap Volkswagen beetle gas filter) after it. Both filters transparent (you can see how dirty they are).

The first filter intercept any garbage coming from the tank before it blocks or damages the pump internal valves, the second prevent small particles (from the pump, it also degrade with time) to get into the carburetor, preventing sticking needles valves and consequently, undesirable fires in the engine bay.

Also, a magnet on the line help help to catch the small metalic particles (btw: I use another big magnet on the oil filter and other on the drain bolt on the carter - that two sourced from IPD - it really works on our old irons).

Small particles comes from rust tanks (car or pump station or dirty storage bin - you not know), internal rust pipes, and also from bits of the seal material used for rebuilld de the tank.

Also, I suggest to clean the carb faucets with some carb sprayer (not recomendable if you have Zenith Stromberg carbs due the spray attacks the diapraghm, sometimes it helps.

Take it with a bit of serendipity. Happy debugging!.

Joaquin
Rojo 121 Amazon
Lima Peru