250 pro xs help again please.

[Jasay]

We had a tournament last Saturday and the engine ran fine up until time to come back in. Luckily I wasn't far from the ramp.

When I started her up to head back to the ramp she had what seemed like a missfire then started running fine again. When I went to get up on plane it was almost like I sheared a key on the prop shift and I heard a pop noise and knocking sound. I idled back to the ramp and managed to get her on the trailer. I was afraid it might be my compressor had given up all at once.

Today test ran it on muffs and it seems fine. Could it just be a shear key broke?

[Jasay]

https://youtube.com/shorts/8yaZs7zeJ...8AZ15FXdiyUxxl

https://youtube.com/shorts/E2BMMHmTh...8b3KKUthUIgvaH

[lpugh]

Quite sure that compressor is bad (crank pin knock) does it build good pressure?

[Jasay]

Pressure was fine a couple weeks ago..

[apdriver]

How many hours on that compressor?

[Jasay]

I'm not sure. I purchased the boat 2 years ago.
mechanic checked it out last year and said everything was good though.

[EuropeanAM]

Pressure could be fine today and still be a bad compressor. Sounds like the crankpin bearing may be failing. And it's leaked enough oil from the crank seal that it's probably done, regardless.

Really wise to plan to have the fuel rails, hoses and direct injectors professionally cleaned and validated (as well as fuel injectors cleaned/serviced). Any metal that passes through the rings in the compressor ends up trapped somewhere in the air side of the system (and once it trashes just one DI, the rest will follow suit in short order).

[Jasay]

Pressure could be fine today and still be a bad compressor. Sounds like the crankpin bearing may be failing. And it's leaked enough oil from the crank seal that it's probably done, regardless.

Really wise to plan to have the fuel rails, hoses and direct injectors professionally cleaned and validated (as well as fuel injectors cleaned/serviced). Any metal that passes through the rings in the compressor ends up trapped somewhere in the air side of the system (and once it trashes just one DI, the rest will follow suit in short order).

Only way to check that bearing is going to be disassembly right? That is the bearing the compressor piston rides on right?

[EuropeanAM]

It's the bearing furthest from the piston (on the crank end of the connecting rod). Also inspect the crankpin itself for scoring, chipping, or missing surface material.

[Jasay]

Screenshot_20231010_172227_Chrome.jpg

These...

[Jasay]

While I'm at it I better check the reeds

[Jasay]

This weekend, I'm going to disassemble my compressor, while leaving most of it on the motor, and check out the crank bearing and crankpin. I'm going to see about what I can do, as far as going ahead and getting a new compressor.

Don, how much is it (if no bad injectors) to inspect and clean my rails?

[Jasay]

20231013_180506.jpg20231013_180516.jpg

Not good. Will that cause the knocking sound?

[lpugh]

As I suspected, I would highly recommend you send the fuel rails to Don (integrity Injection) for service and be sure to replace the 2 drain filters. Also recommend a new OE compressor, I do not recommend repairing with aftermarket parts. Have the oil pump prime procedure performed before starting the motor.
Keep in mind that missing metal went somewhere, oil drains and or thru the air rails..

[Jasay]

Yes I'll definitely be getting all this done.
My only question is, would this cause the engine to not Rev up enough to get on plane?

[lpugh]

I don't think so, perform compression test, inspect/replace plugs.
Preform any maintenance due
check air/fuel pressures! if low pressures it possibly could cause the issues described
Test the belt tensioner (70 in lbs before it rotates to the stop}
scan computer history
test shift interrupt switch for intermittent sticking, may need to warm it up with a heat gun, careful to not get it to hot
check for any water leaks, white residue is a clue.

[SilverFox579]

check air/fuel pressures! if low pressures it possibly could cause the issues described

Absolutely!

[Jasay]

Update!

I checked out what I could today.
Air pressure: 85
Fuel pressure: jumping between 100-105
Checked coils, all good. But,
No change when unplugging #6 coil. Tested for spark and I am getting spark to the plug.
I will check the plugs tomorrow after I go pickup a compression tester.

Are the Harbor freight $30 compression testers worth getting?

[lpugh]

What are using for gauges, must be taken with dual glycerin filled gauges (1%or better accuracy)

[Jasay]

That's what I'm using dual guages, glycerin filled

They may not be the best but this is them.
https://www.harborfreight.com/230-ps...uge-64558.html

On this setup
https://www.harborfreight.com/fuel-i...ter-58760.html

I switched out the guages.