Water not getting to bowl from pump

[Capt Kirk]

Hi, I cannot get raw water from from my pump to the bowl. If I put my hand over outlet there is wateer there pushing my hand off but when I replace the pipe the water doesn't go through. I have checked the pipe and poured water dowm it and it goes into the toilet. If I manualy fill the bowl it pumps away nicely. The brand is an older one possible Jasco.
any idea?
regards
Capt Kirk