Hello Atomic Tom .
Yes follow through some of the tests already mentioned , Matthews next step with the new pump will be the tell tale .
I've never done the thing with propane myself , I normally do vaccum checks and use a smoke pro machine for finding manifold leaks , I'm assuming the vaccum line that you are feeding it in is only a small pipe ? If so its probably just not taking in the volume to affect it so much
Here's the daddy for manifold leaks ....hehe
