3406E Losing Prime

Sure it can .

But I would eliminate the possibility that your filter housing is the issue first.
Join the lines together if it don't fix it then no money lost.
Then I would put a pump on it.

 

Since the check valve isn't in the filter base but was replaced I gotta ask was a new o ring put on it.

 

A guy I run with bought one that didn't come with the o ring. Caused him real similar grief to yours. I figure his hand pump was his original issue till he created the other trying to find it. The o ing off the original check valve nut healed his up. That said his is a 6NZ that has it in the base

 

I have seen them leak around the plunger and not cause any trouble but i won't use that to say that isn't your trouble. Those hand pumps are not actually flat at the base they have an arch to them. I have seen them leak from hole to hole and not externally but that has never caused a loss of prime issue for me only a performance issue.

 

I had a very similar problem after we went through my motor. Ended up being a new transfer pump. The check ball under the pressure spring was letting it loose prime. We probably shouldn't have put an new pump on with a rebuild when the old pump was still good. Did end up putting the old pump back on and problem solved. After we changed several other things including all the lines.

 

Perfect!!

I figured it was better to rule out that housing first.
Transfer pump is easy fix. Aren't you glad you didn't pull all your injectors now . Lol That would of been bad .

Glad you got it fixed!