Rpm’s off

[Bradb571]

I seem to be having an issue with my rpm’s being off to each other. I changed the spark plugs and it didn’t help. My port motor is definitely lower than the starboard. I’m not having any vibrations. Any ideas? 2005 sundancer 340 with twin 8.1’s. Thanks!

 

[Nater Potater]

Do the tachs agree with your ears? In other words, if you pull the starboard engine back until the tachs match, does the exhaust note sound like it's also coming into sync? I ask only because the factory tachometers aren't always to be trusted.
Has anything happened/been done to the port engine recently? Did it come on suddenly? Fuel filters been changed in a while? How many hours on the engines? If high, I'd start with a compression leakdown test. You can lose some compression on one cylinder without it creating an obvious vibration.

 

[Bradb571]

This did seem to come on suddenly. The motors have about 500 hours on them. I seeing the rpm’s on the gauges as well as the smart craft display. Seems the higher the rpm’s, the more difference between them. They seem fine while at idle. It’s been a while since the fuel filters have been changed so I can start there.

 

[R-and-R]

This did seem to come on suddenly. The motors have about 500 hours on them. I seeing the rpm’s on the gauges as well as the smart craft display. Seems the higher the rpm’s, the more difference between them. They seem fine while at idle. It’s been a while since the fuel filters have been changed so I can start there.

When I had this issue on my 2001 with 8.1s, it turned out to be the fuel pump. Maybe time to find a professional to diagnose it for you.