Hey, long time lurker here. I was hoping to get some input on a problem I'm having. Any help would be awesome!

I work on irrigation systems and have run into a problem on a lake pump. It's an F&W jet pump, model CPJ15, with a pressure tank and switch attached. The glass over the gauge is busted and doesn't register any readings, but the pump primes and runs just fine (at least it seems that way). However, when the pump is running and I have a spigot open on the main line, it barely flows.

The only thing I could think of that may be causing it is an old strainer/foot valve or a hole in the suction line. Is there anything else I could try if those ideas don't work?