air in fuel line

[subcon]

hello this is Michael Di Sisto with a first post (thread?)
After finding out about my fuel tank corrosion and getting a mechanic to take apart and clean the carburetor and hooking up an outboard tank to circumvent the old fuel supply, I still had the motor stall after a short running time.(again)
After attending the May workshop and purchasing a new carburetor, which I installed and got to start right up,it also stalled after some minutes.
In between cursing my fate,I read a handout from the workshop, which mentioned a hand primer to overcome possible fuel pump cavitation?, resulting from air getting into the fuel lines
A little outboard tank conveniently has a hand primer which I used to maintain pressure and lo and behold the motor did not stall.

Can anyone tell me:
1. Do I simply have to find where in the (all metal) parts I have a leak to solve my problem?
2. Who(what) is the likely culprit?
Suggestions of any kind are welcome

[JimH]

Air in the fuel lines

Greeting Subcon:
I have had exactly the same experience. I rebuilt my carburator, added a new fuel/water separator, new fuel lines with a priming bulb and cleaned the sediment bowl. The engine would start and run for a few minutes then begin to run down and stall. It seemed that the engine simply stopped getting fuel and would only start with the choke close and would stall when the choke was opened. The access to the carburator is terrible in my boat and after much of head scratching and retracing my work I found the problem. The two bolts that hold the carb to the manifold were not tight enough and allowing air into the system. It was very difficult to get a wrench on the bolts particularly the aft most bolt so use allen head bolts with a modified allen head wrench, which worked to tighten things up. The engine stated up and with some minor adjustments to the main jet, now runs perfectly. The problem air in the caburator.