Won't stay running

[Luv2cmwork]

1975 9.9 Evinrudee. Hasn't been used for roughly 10 years. Got it started, replaced gas, new plugs, sea foamed in the gas. Gor it in the water and it ran great for about 3 minutes and then died. Continued to do that. Started pretty goods, ran OK at idle, but when I opened it up it would run great for a minute or two and then bog down and die.

If I kept pumping the primer bulb, it would run just fine.

There are no leaks anywhere.

When I opened the fuel can, I could hear air as if pressure was built up. Don't know if was a negative or positive pressure, but definitely pressure.

Took it home to think it over.

My first thought was: either a carb kit or a fuel pump. But then I wondered if maybe the pressure on the tank was a bad thing.

This is not my motor...I'm borrowing it, so I don't want to put too much money into it. I hope to take it out tomorrow and loosen the fuel cap a bit to relieve that pressure to see if that helps. I thought maybe it NEEDED that pressure, but after reading some other boards, that might actually be a problem???

Any other ideas?

Thanks in advance

[Elton Smith]

Sounds like the tank is not vented.Try running it with the gas cap off.

[Luv2cmwork]

Took it out again today. Left the gas cap loose. Better maybe, but still bogged down and died.

Best next guess? Fuel pump or carb kit? Or both?

[Elton Smith]

When it boggs down try pumping the primer bulb.That will tell if the fuel pump is not working.If it runs good the the fuel pump is bad ,after you pump it.