Tiny Bubbles in my fuel pump bowl

[GPS]

 So I took my 72 twin cam out around the hood this weekend and when I got home she showed me yet another puzzle. When I got home and shut her down I opened the the hood to check the engine for any leaks as I always do. I noticed small bubbles rising up in the glass bowl of my stock fuel pump. It looked like a glass of seltzer or an IPA. Open the gas tanks thinking there my be a vacuum somewhere but no changes. Started her back up again and got quite a bubble  show as the fuel bowl filled a little more. Never having seen the inside of a fuel pump, maybe this is normal??? Just want to not lay in bed at night and worry about it as I would normally do. I did remove the pump a few months back to clean up an oil leak from the block by replacing the gasket and resealing. In the process I took the pump apart and it all looked ok. The car seemed to run fine, so I don't think it is effecting it, but still curious. Does it need to be rebuilt?

[Grumblebuns]

In all of the early years of TC ownership, I never noticed any air bubbles in the glass bowl. Possibly air is getting into the fuel lines under vacuum? Have you checked your fuel line connection to the fuel pump for tightness? It may not be worth rebuilding the mechanical fuel pump but instead order a replacement mechanical fuel pump. Unfortunately, I believe they do not come with the glass bowl. The other option that many of us have gone to in to install an electric fuel pump.

[4129R]

Those mechanical pumps are still available with glass bowls. SJS.

If there were any leak on the pipework, petrol would leak out, all over the hot exhaust and whoomph.

Been there, done that !!!

[Bainford]

Grumblebuns may have your answer. I would check all fuel line connections upstream from the pump; at the tanks, the lower fuel 'T' (at the fuel tank cross-connect), at the fuel filter, and at the pump inlet itself. The inspection should include any threaded connections or adaptors at these points, as well. I would also inspect very carefully all fuel lines upstream of the pump for pin holes.

Is the issue more prevelent when the tanks are low on fuel? That would be another clue.

[Kendo]

If the pump is original and the diaphragm is starting to leak, would that produce bubbles?