Why does time dependent(transient) simulation of fsae intake manifold result in flow in only two runners?

Hii All,

I was doing a time dependent flow simulation for our manifold. The inlet was set to ambient pressure. The runners were given a data in which the data upper time limit was
0.01365, with steps of 0.000525. The time dependency had a phase difference of 90 deg every cylinder. After running the simulation, I explored the results through a flow trajectory which shows the fluid flow only in 2 of the runners.

It would be great if anyone could help me figure out what else have i left out (like some goal is to be defined). Also the maximum calculation time was set to .017 sec.

Any help is greatly appreciated.

Thanks,

Samio

SolidworksFlow Simulation