2021 250 Pro XS 4 Stroke Issue

[dkeppler1087]

S/n : 3B051199

So the motor currently has 12 hours on it and this issue has been there since day 1. It randomly shakes pretty hard at idle while in gear, doesn’t do it always just sometimes. Runs perfectly fine otherwise jump on pad run 70+ mph. Bought the boat from a dealer 9 hours from my house and every local merc dealer I’ve reached out to lately isn’t taking work currently or the wait time is weeks from now. Any thoughts? Had one local dealer tell me if there isn’t an alarm it’s fine just run it. I have to think there is some issue going on. Any help greatly appreciated.

[EuropeanAM]

Is this a repetitive shake, or more of a "clunk"?

OR, does it repeatedly shake as if the engine were skipping?

[dkeppler1087]

Is this a repetitive shake, or more of a "clunk"?

OR, does it repeatedly shake as if the engine were skipping?

I would say it’s a repeatedly shaking. I’ll see if I can get a video.

[EuropeanAM]

In the meantime- not a bad idea to make a visual inspection under the cowling for anything that doesn't look right.

Make sure none of the plug wires are loose at the plug end (IMPORTANT: DO NOT pull or tug on the WIRES, as this damages them. Grab the SQUARE RUBBER BOOT and make sure it's seated and clipped on the spark plug).

If a boot does not clip properly on the plug, the wires must be replaced.

[djb750]

Also - you might just remove the prop, inspect, and then re-install prop to the correct torque.
If it's an SSR hub, then: http://www.bbcboards.net/showthread.php?t=927571

When I first purchased my last boat (used), the oscillation that translated thru the hull when it was idling in gear was really noticeable. And only at idle, in gear. In fact, from the casting deck up front it felt like the whole boat was wobbling.
I installed a new flo-torq hub on that one and it was night and day different.

It may or may not be the issue, but you may as well do a few things just to cover your bases.

Good luck

[dkeppler1087]

Just in case this happens to someone else. My fuel pick up line had a crack in it from the factory. It was sucking air messing up the air to fuel ratio.

[thommo59]

Just in case this happens to someone else. My fuel pick up line had a crack in it from the factory. It was sucking air messing up the air to fuel ratio.

Thank you for reporting back with the result

[EuropeanAM]

Just in case this happens to someone else. My fuel pick up line had a crack in it from the factory. It was sucking air messing up the air to fuel ratio.

Would this be the fuel pickup in the fuel tank, or the line from the tank to the engine connection, or something further down the line?

[dkeppler1087]

Would this be the fuel pickup in the fuel tank, or the line from the tank to the engine connection, or something further down the line?

not 100% sure but believe it was at the tank or in the tank. It was a 90 degree fitting that had a plastic tube connected to it and the tube had a crack where it was pushed up on the fitting.

[EuropeanAM]

Probably the pickup tube for the fuel tank. Does happen... though it doesn't help much, those are a BOAT fuel delivery system item (not directly engine related, though the do affect the engine if they don't work properly).

Glad they're able to get you taken care of!