Motor not staying primed after 2 hours

[Project11]

I am new to the forum and bought a boat running a 200 Yamaha 200 EFI. At first I thought it was out of gas as I test drove the boat and had it delivered and broke down on the ramp after 100 yds. Put about 15 gallons at the ramp and I “limped” to the house. It would run barely. Next day changed motor filter (fine) and dumped gas filter (no water or trash) pulled plugs and looked fine. I then changed both fuel pumps and it ran for about an hour and then started limping. If I squeezed the primer bulb, I could get it to restart. This might be key.. next day, ran perfect for an hour then the same. I mean perfect, bulb seemed to be losing prime. Changed primer bulb and all the way to engine and then ran for 2 hours. Repeat. Back to square one. Primer bulb not staying hard but seems to have some gas but also remedies itself after pumping . Not running hot foe sure and good stream. The first 1-2 hours a day it runs perfect. 250 total hours. After 2 it takes pumping to limp back

 

[alldodge]

If I squeezed the primer bulb, I could get it to restart. This might be key..

That would be the key from me also
The primer bulb should pump up hard for the first start, once the motor is running the bulb should not stay hard. The fuel pump should be able to suck/pull fuel from the tank without issue.

Boat probably has a mai tank and not a portable type. Remove the antisiphone valve from the tank. The valve will have the rubber fuel line attached. It has a spring and ball inside which can get clogged up

 

[Project11]

That would be the key from me also
The primer bulb should pump up hard for the first start, once the motor is running the bulb should not stay hard. The fuel pump should be able to suck/pull fuel from the tank without issue.

Boat probably has a mai tank and not a portable type. Remove the antisiphone valve from the tank. The valve will have the rubber fuel line attached. It has a spring and ball inside which can get clogged up

 

[Project11]

I really appreciate you getting back to me on this as that will be my next step to try. Everything that you’re saying is true but I have replaced the fuel pumps the bulb lines motor runs fine and thought about that in the tank and I’m not familiar with that but I did take the top of the tank off and has a little lever and a rubber grommet on the bottom and I’m trying to figure out how to get that out or replace it or something. Seems like that’s a logical step I just need to do a little research but I really appreciate that

 

[alldodge]

Didn't understand what you said about your tank design
Try this, get a 5 gal can and put a fuel line in and see if there is any issues.

 

[Project11]

Sorry,

I was walking and not making sense. I have access to the tank in the middle of the boat. I am not sure where the anti siphoning spring is but I do have access to the tank in the middle with an access door. I will do some more research but it sounds like you might be on the right track. It might not do it for an hour or 2 so the five gallon might not work. I will try the first thing you mentioned