Looses power after a few minutes

[RyanTosi]

Couldn’t find what is happening to my boat In here. So I have an 05 wakesetter, after about two laps around the lake (3 minutes) the motor will loose power under throttle. So if you hold open throttle for about 20 seconds the motor drops power hard. Let off completely, give it a few seconds and the boats rips out, but happeneds again 20 seconds. 

New Plugs, distributor and cap and exhaust manifold on starboard side. About 12 hours on them.  

Compression: 

1:165

2:145

3:150

4:150

5:150

6:155

7:115

8:155

[Creekrat]

Unfortunately #7 looks like it’s in the way out. 80% of the next lowest cylinder and 70% of the highest. 

 

On your loss of power i would start by looking at the fuel system first. Quite possibly a fuel pump.  Next would be to check spark/timing but I’m guessing it’s a fuel delivery issue. When it looses power does it do so like you were just throttling down or does it spit and sputter?  Also, does it idle well all the time?  Even right after the loss of power?

 

I had had a similar problem with an older mastercraft but it would take like 2.5 hours for the problem to rear its head and it ended up being the starter solenoid. Once it got good and warm it would quite delivering power to the ignition. Ended up wiping out the starter before we figured it out. 

[minnmarker]

Fuel filter?  On an 05 they're really easy to replace.

Check the pump inlet screen while you're back there.

I would retest #7.  115 is pretty low.  Maybe it was hard to reach and the gauge wasn't straight?

[RyanTosi]

3 minutes ago, Creekrat said:

Unfortunately #7 looks like it’s in the way out. 80% of the next lowest cylinder and 70% of the highest. 

 

On your loss of power i would start by looking at the fuel system first. Quite possibly a fuel pump.  Next would be to check spark/timing but I’m guessing it’s a fuel delivery issue. When it looses power does it do so like you were just throttling down or does it spit and sputter?  Also, does it idle well all the time?  Even right after the loss of power?

 

I had had a similar problem with an older mastercraft but it would take like 2.5 hours for the problem to rear its head and it ended up being the starter solenoid. Once it got good and warm it would quite delivering power to the ignition. Ended up wiping out the starter before we figured it out. 

It stays at the same power level when lost. And when  You let throttle off the idle goes up and does for a few seconds then goes normal. At start up normal, backing out good. I’ve been thinking fuel pump, probably going to change out filters first. Previous owner added a inline filter just under the oil filter. 

[RyanTosi]

17 minutes ago, minnmarker said:

Fuel filter?  On an 05 they're really easy to replace.

Check the pump inlet screen while you're back there.

I would retest #7.  115 is pretty low.  Maybe it was hard to reach and the gauge wasn't straight?

I will retest 7 and let you know. It took double the time to get the number then the rest.