So I’m pretty mechanical, but this one is getting me. 115 Mercury efi 4 stroke. It fires right up, idles fine, gets on plane, may run for 5min or 1min, but then cuts out. I can go back to idle for a minute and same thing, gets on plane and then at some point cuts out.

I’m leaning towards fuel pump or coils going bad. I’ve changed spark plugs, fuel, filters, had the injectors cleaned.

No boat mechanic but could be a bad fuel line closing up internally.

Send it to hevi hes free 🤣

You've got crap in the tank. You need to drain it and clean out the gunk.

That was my first thought, but how is it getting through the various filters?

This, or a filter you haven't found, yet. The pickup or the filter is clogging itself as you draw more fuel...when the engine dies or idles, the sediment falls back out of the filter/pickup until you throttle up again and increase the suction head.

Pickup is a good thought. I have a portable tank. I think I’ll hook it up to it and see if it runs. If so, then I know it’s at the tank.

What year model engine is it?

Could it be a crack in the tank or line causing it to suck air? Mine was cracked and had the same symptoms except it was a rough idle most of the time. Plug wires on good?

I’d lean toward fuel issue, is it old enough to have prime bubble in line?

A crack in the tank, line, or pickup tube would cause the engine to run worse as the fuel level depleted. Check to see if it has mercury gray fuel line on it. Mercury’s fuel line sucks because the liner of the line falls apart inside and packs into the lift pump.

Does it get worse when turning the engine in either direction?

Does it get worse when you idle a while, or maybe run it hard a while.

Have you had anyone hook a laptop to it? If it’s an ignition issue a laptop should show it.

Sounds most likely like a fuel issue to me.

I’ve had the same issue with my boat a few years ago. Took forever to figure out but it was the inner liner of the main fuel line collapsing and cutting of flow. You couldn’t tell from the outside of the line, but when I was taking the bulb off I could see the loose liner a little way in the line. I changed out all of the lines and it ran great.

Thanks guys. It acts like it’s getting air in it or starved for fuel for just a second. It’s jarring when you are running wide open and then it just stops for a second. The first time I thought we hit something. It’s a 2006. It’s irritating because every time you try something, it’s a trip back to the lake for a test run.