1998 5.7 Volvo - Four Winns Engine slows at higher RPMs

[JScott75]

My 2000 Four Winns boat slows at higher rpms. Around 3500 on the tach it will auto shut down, not die, just slowdown. Runs smoother than a sewing machine at all rpms below 3500.

I searched the forum and found a few with the same issue, but no exact remedy. The only step I have taken is to replace the fuel filter, but no help.

Is it the motor control panel shutting me down? Does that mean electronics? Fuel pump(s)?

 

[Scott Danforth]

JScott75, we will need to know a bit more about the motor. specifically, fuel injected or carbureted.

what you are describing sounds like its fuel related.

plenty of stickies at the tops of the forums on low WOT.

when you replaced your fuel filter, did you inspect the contents of the filter?

 

[bruceb58]

Volvo has a SLOW mode that does this when it senses high temp or low oil pressure but the RPM it limits it to is 2500 RPM.

BTW...the sensors it uses for this are not the same as what are used for gauges so your gauges would look correct if one of these switches failed.

 

[JScott75]

Thanks Scott,
The motor is fuel injected, throttle body injected to be exact. It is a 1998 5.7 OMC/Volvo.
I did check the old fuel filter but didn't notice anything out of the ordinary. just gas, no signs of water.

Thanks Bruce,
This sounds more like what I am dealing with. Some sort of a motor protection/safety issue. It is only a temporary slow down. Everything runs fine up to about 3500 RPMs then it will back off, then pick back up.

I really appreciate your help. This is my first boat wrenching experience, I am having fun investigating and learning.

 

[bruceb58]

You can always pull the wires off the oil pressure and water temp switch to see if that is what is causing the issue. Problem is that it should be occurring down at 2500 RPMs.

Like I said before, these are different that the senders for the gauges. If you pull a wire off and the gauge stops working, you pulled the wrong wire off.