Randomly loss of power after a period of time and sounds like it's not getting fuel

Hi, I have an early 1980's Marina 90, 2 stroke, 3 cylinder, outboard. It recently started giving me random trouble while out. I would be out for a while fishing, then once i decide to return after a few hours, it starts to play up. It starts fine, but when i put then throttle down full, it dies off, runs like it is starving and losses speed. If i back off the throttle it will usually be ok again until i try to go fast again. This has happened the past 4 times i have been out. As soon as i stop and idle, including with the engine reving at near full speed, it seems ok. But then when i go to take off, it dies off again. It is always on the return trip when it plays up. I have changed the spark plugs and made sure fuel is flowing through the lines. It does not stall, just losses power and sounds like it's starving.

Of course when i take it to the mechanic, it runs fine, but i can't afford to pay him to spend hours hoping to find a random problem. I can only do minor mechanical stuff myself.

Any ideas please?

Re: Randomly loss of power after a period of time and sounds like it's not getting fu

First guess is varnish in the fuel or bad fuel. You can check the squeeze bulb when this happens. What is it's condition? If collapsed, you have an obstruction in it or somewhere back into the tank. If not squeeze it and see if things improve. If so, fuel pump or fuel filter clogged, or squeeze bulb defective. Otherwise varnish or fuel would be the suspect.

Mark