Which vacuum are you talking about vacuum in the fuel tank which there shouldn't be any or the vacuum from the fuel pump?

There shouldn't be any vacuum in the fuel pump only the intake side which sucks fuel.from the fuel tank.

You need to be more specific on which vacuum? As its no good guessing what member post.

 

I guess I should have made the word vacuum plural, as in vacuums! There was no vacuum on the inlet side of the pump and obviously there was no vacuum on the outlet side of the pump because, as I mentioned there were bubbles blowing into the glass filter bowl as the engine was cranked. Vacuum is not an issue.

Vic

 

I haven't seen a fuel pump with a glass bowl on top for 50 years that is the old AC fuel pump where you could buy a service kit for.

Which you change the diaphragm and inlet and outlet valves along with the rubber seals.

The vacuum on the inlet pipe is made by the fuel pump to draw fuel from the fuel tank.

There should be a small pressure on the outlet pipe on the fuel pump around 5 psi so the carburettor gets filled.

As I've said this isn't an easy question to answer on a forum.

I would check you have no restriction on the fuel pipe/connectors coming from the fuel tank.

 

This fuel pump works just fine until it gets hot. I have no way to test a hot pump with for vacuum or pressure with a gauge. I have ordered a new fuel pump and will let you know what happens with it. Thanks for helping.

Vic