6lpa won’t rev Idles fine (1 Viewer)

[240z]

Hi All,
I have a 6lpa 315 that I got used coast guard. Had a blown head gasket that we changed.
No leaks now, idles and starts fine but will not rev past 1200 unless primer bulb is pumped while running. If bulb is pumped while running it will hit the limiter.

Testing on garage floor so no load.
Any ideas on issue?
Thanks,
Frank

 

[TheBussman]

put clear fuel hose on and see if air is getting pulled in to the system. the primer can leak air.

 

[240z]

put clear fuel hose on and see if air is getting pulled in to the system. the primer can leak air.

Switched primer over today to second motor works fine. So ruled that out.
Leaning toward pump now.

 

[TheBussman]

Some VE style injection pumps need a lift pump, I'm not sure if the yanmar pumps are that way.