I have a rebuild fuel pump. It is not leaking, but the fuel un-primes or leaks down and the pump un-primes and will not pick up. If I suck fuel though the system past the fuel pump it will work fine and last a day or 2 only. I'm thinking the check valve may be leaking but not sure. I know it will bypass the air with some force. The fuel selector leaks and I have tried to seal it with a sealant on the outside.

I would go over everything in the fuel system and make sure it is clean, clear and working properly. Be careful - you don't want to run it lean and trash an Engine.

Could the leaking petcock be sucking air? could the pickup tube be blocked? Perhaps the pump is bad. Is the pulse line sealing well on both ends?

Take your time and go through it all.

Good timing -- I have had a lot of fuel supply issues with the death machine lately and have done a lot of fooling around. All four of my Chinese pumps only put out 2 oz.

One of the things you could try is to get one of those check valves that you get with a brake bleeder kit.
Put it in the pick up line. That's a good test to verify if your pump valve is leaking.

Watch out for those leaks you're talking about ------- FIRE !!!!!!
A reasonable amount of safety must always be kept in mind.
CO

How much fuel should I be pumping? 3 oz per?

4.5oz or more over 10 seconds

4.5 oz at idle? in 10 seconds? I got 4 in 30 seconds. I did not see this before I went riding. It lasted 3 miles and lacked power but then ran hard I think I smoked the piston. It stopped running and makes a weird noise. when cranking. I would bet it was 4 oz in 10 seconds at one point but when it was idling it was not. The fuel pumps are rebuilt factory but leak down if not running and will not prime unless I suck fuel into them from the overflow line while pinching the carb line. as air in the carb flows back up the line. The other 350 ran ok too but I'm not sure the fuel is flowing enough there either.

When you measure the fuel flow on a pump you don't do it with the Engine running.
You use the starter only and you use a stop watch to measure the 10 seconds.
You smoked the piston because it leaned out.
It loses its prime because you have an air leak in the line some place or the valve in the pump is probably by passing.

Like rmesser said: check everything. It could also be some of the stuff he mentioned.
CO

Edit: You want 4 oz in 10 sec like ZeroClient said.

Thanks. I forgot to check the post before heading out. Dumb move. I need to go over everything again. I added a second check valve on the other 350 and it stopped leaking down so my original check valve is bad I guess. I tested it and it seemed to work but??? so I have 2 on it right now. I should have been the one testing the Oddy and not my son. I had made some runs down the street with success but we went from 4000' to 6500' in the mountains. I figured it was to rich at one point also the fuel mix was around 25 to 1 with the synthetic oils.

4000' or 6500' it wouldn't make a difference. You were ded with a low fuel flow.
Also that 25/1 is way oil rich.
Just my opinions.
CO

Edit: Based on what I read here you must have some homemade or other check valves in the pick up line or else where in your system. I like this creative out of the box thinking, but if your system requires this stuff then obviously something is very wrong. It's a good way to test stuff but once you know you have a problem and have traced it down then you gota fix it and not run like that. The end result could be catastrophic.

It is oil rich. i was thinking of break-in time. Also old habbit 20:1 thinking and could not remember if people were doing 32:1 or not. So I tried to split it. Now i get to see if i need to redo my cylinder or not.