Port engine stalls while running after a while

[Ctmangrum]

So ive been running my boat in open water last few days and for an unknown reason will just shut off. Doesn't get hot, oil pressure looks norm, has gas. I can start it again within 5-10 mins and it will run for a while then shut off. Any ideas? Thanks.

I have twin Ford 351's in a 1976 Carver Mariner 2896

[Ctmangrum]

Just dawned on me that i remember hearing an alarm as Im restarting the engine. I don't hear it when I initially start the engine and dont rememeber reading about it in the manual.

[tomschauer]

A couple thinks to look at / think about.
Are you running it hard when this happens? (high 3000's or over 4000' rpms?) If so may be getting hot, you can't always trust gauges especially on an older boat.
Fuel filters and tank pick up screen. Again, does this happen when running hard? tanks can have "junk" that will clog the inlet screen when drawing a lot of fuel. When you shut it down for a bit, it will fall off the screen and you can run again.

I would look into the fuel filters and the fuel system first.

[Ctmangrum]

I will tomorrow. Sorry, not sure where the fuel pick up screen is. I pushed it to 13 knots. Other engine runs fine. I just changed the fuel/water separators a week ago. Didnt seem to have a problem. Appreciate the advice, ill take any Advice you got.

[tomschauer]

Pick up screen is in the tank.
Do you have one or two tanks?

[tomschauer]

If you have two tanks, do you have the ability to switch tanks? If so, switch the tank feeding the problem engine to the tank feeding the good running engine and see it the issue goes away.
If this is a new to you boat, could be bad gas and water in the tank also.

[Ctmangrum]

New to me boat. Two tanks. I would assume that if i had bad gas, it would effect both engines. Ill try switching tomorrow. I put all the gas in, had it for a few months.

[tomschauer]

If you have two tanks, most likely each engine pulls off of its own tank. (port / starboard) You may have a tank selector switches that allow you to change which tank each engine draws from. If you have these switch the bad running engine to run from the same tank as the good running engine and it the problem disappears, you know you have a problem in the other tank.

[Phrancus]

QR_BBPOST I just changed the fuel/water separators a week ago.

problem occured after that?

[Steve2020]

Could be plugged tank vent line. Quick check is when engine stops open fuel cap to release negative pressure then try to restart engine, spiders love to plug vents. Happened to me twice.