I have a 1978 Sea Ray 220 Overnighter, it has a 2001 5.7L Mercruiser with an Alpha One. The engine was rebuilt in 2016 as well as the carburetor, new plugs, distributor cap, rotor, any part that was "suspect" I replaced. Here is the problem and it's really got me frustrated. Put the boat in the water, it starts up right away, no long cranking and trying to get fuel to the 2 bbl carb, we go out on the water, runs great for about 20 minutes, then it does a few things. It will run fine if I keep it around 1500-2000 RPM, when I open up the throttle it seems to be starved for fuel and stumbles, and sometimes backfires through the caburetor. More important information, when I attempt to fill the fuel tank I have had it spew fuel out of the vent the last two times. I recently replaced the fuel vent, and I removed the line and made sure it was clear, and it is. I was on deployment with the military for a year, when I put the boat in storage it had about half a tank and I put in sta-bil in the tank, I also put sea foam before taking it out this past weekend. If I run it slow it runs GREAT, but if I try to open it up, it stumbles, but ONLY after being out for a while. I didn't change the configuration of the vent system when I changed the vent. It's frustrating, any ideas?
