PCM 5.7 loss of power under load higher than 2000 RPMs

[Bullbill99]

Boat starts and runs fine at idol. When running down the lake at 2000 and higher RMPs it will stumble/stutter and red light comes on. If you pull it to neutral it idols fine. If you take back off it does the same thing. Does not do this running down the lake less than 2000 RPMs. Anyone have any ideas please? Thanks!

[hal2814]

It idles fine in neutral but will it go above 2,000 in neutral?

[James]

Responders will need more info to sort out your issue. I assume you have an Excalibur 343. Here are some thoughts/questions... Which “red Light” comes on? Did the problem develop suddenly? Has the boat been maintained? What are what are your gauges telling you... oil pressure, engine temperature, volts etc. Is the boat going into “limp mode” due to an oil pressure/sensor issue or over heating issue due to a bad impeller? Can you get it to run at any higher RPM’s while it is in neutral? Need to consider and it could be as simple as the Potentiometer/Throttle controller position sensor going bad.

[NautiqueJeff]

Are oil pressure and temperature OK? If so, you either have a bad temperature switch or oil pressure switch, and it is throwing your boat into limp mode. Disconnect one of those switches and see if the problem goes away. If not, disconnect the other one and try. Once you figure out which switch is bad, just replace that switch. Leaving the bad switch disconnected will allow you to use your boat while you wait for the right switch to be delivered.

These are the SWITCHES, not the SENSORS. Sensors feed the gauges, switches control the Check Engine light and control limp mode.

[Chrisrog]

Is the fuel system healthy? Could loss of a fuel pump cause this issue?

[Bullbill99]

Are oil pressure and temperature OK? If so, you either have a bad temperature switch or oil pressure switch, and it is throwing your boat into limp mode. Disconnect one of those switches and see if the problem goes away. If not, disconnect the other one and try. Once you figure out which switch is bad, just replace that switch. Leaving the bad switch disconnected will allow you to use your boat while you wait for the right switch to be delivered.

These are the SWITCHES, not the SENSORS. Sensors feed the gauges, switches control the Check Engine light and control limp mode.

Oil pressure normal, engine temp is good. We replaced both fuel filters the end of last year and ran fine the last time before we winterized it. This year after unwinterizing it, it ran fine but didn’t run it hard all day, just over 2000 RMPs once - no issue. Second time out as soon as over 2000 RPMs it did the same thing.

[Bullbill99]

Responders will need more info to sort out your issue. I assume you have an Excalibur 343. Here are some thoughts/questions... Which “red Light” comes on? Did the problem develop suddenly? Has the boat been maintained? What are what are your gauges telling you... oil pressure, engine temperature, volts etc. Is the boat going into “limp mode” due to an oil pressure/sensor issue or over heating issue due to a bad impeller? Can you get it to run at any higher RPM’s while it is in neutral? Need to consider and it could be as simple as the Potentiometer/Throttle controller position sensor going bad.

Yes Excalibur 343... the main red circle light on the dash comes on. Yes - the problem developed suddenly. Yes the boat gets maintenance/serviced every 50 or so hrs. All gauges are showing normal pressure/temp/volts. Assuming pressure/sensor as impeller was just changed. Have not tested the neutral position thoroughly but believe the last time it did run ok at higher RPMs in neutral.

[Bullbill99]

Is the fuel system healthy? Could loss of a fuel pump cause this issue?

Yes that’s what we were considering... changed the FCC filter and inline filter both.

[2001SAN]

Bad oil switch or temp switch putting it in LIMP mode. Bad switches will not affect the sensors that fed the gauges. Seen bad oil switches do this several times.

D

[Bullbill99]

Are oil pressure and temperature OK? If so, you either have a bad temperature switch or oil pressure switch, and it is throwing your boat into limp mode. Disconnect one of those switches and see if the problem goes away. If not, disconnect the other one and try. Once you figure out which switch is bad, just replace that switch. Leaving the bad switch disconnected will allow you to use your boat while you wait for the right switch to be delivered.

These are the SWITCHES, not the SENSORS. Sensors feed the gauges, switches control the Check Engine light and control limp mode.

Do you happen to know the part number for the switches by chance? Thanks again!