Planing and then stalling out

[Threadgill]

2003 volvo penta I/O 5.0 GLC
take it on the water (gulf) open it up to planing speed 3-5000 RPM for about 15-20 min., Turn around a comeback and it bogs down and dies. It will then turn over but not start. Towed in 3 times. 2 barrell Holley carb. Get back to dock, if pour fuel straight in top of carb it works
1. Changed all plugs
2. Changed oil and fuel gage, both quit working during this process
3. Carb business cleaned and rebuilt carb
4. New fuel pump and fuel filter
5. Dumped 80 gallons of nasty looking fuel, replaced with 20 gallons, sea foam, and stay-all
6. New fuel line
7. New fuel pump fuse
8. Detached fuel line from carb, turned key and good fuel flow
9. Cleaned distributor cap
Some are saying to check fuel anti syphon valve in tank, ignition coil, fuel pump running properly. May be a venting blockage, wiring shorted on fuel pump, spark plugs not sparking right, want me to check for suction by gas cap. The tank is a 104 gallon tank

 

[alldodge]

Howdy

8. Detached fuel line from carb, turned key and good fuel flow

Was this done when the motor was not starting or after its back on the trailer?

To check if your drawing a vacuum the motor must be running until it starts to die. With motor OFF the gas cap is removed and need to listen of air sucking in.

From your posting my first guess is it is the tank vent.
Reasons:
Run good for 15-20 minutes before it happened
Can pour gas in and it will run
Gas does flow to carb after sitting for some time

 

[kenny nunez]

Remove the suction tube from the fuel tank, inside the tube there may be a small screen filter about 1” long. You will have to unscrew the tube from the 90* elbow and push a small rod through the tube to remove it.
Also as A-D said the anti siphon can also cause the same problem be sure to replace it with a brass style and not aluminum.
The one way to narrow down the source of the problem is by having a 6 gallon out board tank that you can install to the fuel filter after removing the line from the tank when the engine stops then prime the engine with the primer bulb and see if things improve.