Zero fuel pressure?

[Reserector_]

I'm stumped.
Mercruiser 3.0 with new mechanical fuel pump and rebuilt Holley carb.
The first time on the water, it wouldn't get on plane. It seemed to starve.
I added a test fitting to check fuel pressure and saw zero psi. So I replaced the unbranded pump with a Carter. STILL not showing pressure at all.
Any thoughts as to why no reading?

There is fuel in the gauge's hose, so I know it is connecting.
I tested the gauge on the trailer tire and it showed pressure.
The engine starts right up and runs. I'm just not sure if the pump is keeping up.
View attachment 20210620_162635.mp4

 

[Reserector_]

UPDATE: It has pressure, now!
I did a flow test:
I disconnected the line before the gauge, added a hose and a quart bottle. Supposed to run the engine for 45 seconds and get a half bottle. At 30 seconds I had a quart! Plenty of flow.
I reconnected the lines, restarted and saw 12psi on the gauge. Shut it off and it slowly dropped. Restarted and it went back up to 10 or so.
I'm stumped again, but satisfied.

 

[Scott06]

UPDATE: It has pressure, now!
I did a flow test:
I disconnected the line before the gauge, added a hose and a quart bottle. Supposed to run the engine for 45 seconds and get a half bottle. At 30 seconds I had a quart! Plenty of flow.
I reconnected the lines, restarted and saw 12psi on the gauge. Shut it off and it slowly dropped. Restarted and it went back up to 10 or so.
I'm stumped again, but satisfied.

maybe not primed originally? or anti siphon valve is sticking

 

[Bt Doctur]

any more that 4-6 psi will cause issues.

 

[Reserector_]

I don't trust that reading. Also, it did not hold at that pressure. By the time I fixed a leaking fitting and tested again, it was reading zero again.
I removed the gauge and found that the tip had broken and was not pushing down the pin in the Schroeder valve.


I did also determine that my timing and idle mixture were pretty far off. The engine sounds much stronger now and reacts to throttle with enthusiasm. I am ready to try it again.
I will have to find a replacement end for my gauge before I can check pressure.

 

[Scott06]

I don't trust that reading. Also, it did not hold at that pressure. By the time I fixed a leaking fitting and tested again, it was reading zero again.
I removed the gauge and found that the tip had broken and was not pushing down the pin in the Schroeder valve.
View attachment 344733

I did also determine that my timing and idle mixture were pretty far off. The engine sounds much stronger now and reacts to throttle with enthusiasm. I am ready to try it again.
I will have to find a replacement end for my gauge before I can check pressure.

I had the same issue on my jet ski measureing fuel pressure. Maybe just put a T in and connect a rubber hose, plug it when done . At least you are making progress.