Originally Posted by eliezerrosario
No, the stock fuel pump has the check valve on it....and I believe walbro's also have this "built in" check valve. If you don't have one, it could be the cause for the pressure drops.
Here is a link of what I'm talking about
Look at pages 11 and 12
There's only 10 pages when I load it.
The check valve is in the pump itself and you're likely not getting it out and shouldnd be a restriction.