454 Horizon rpm jumping

[370]

Hi All,

Twin ‘98 7.4 454 Horizon Engines

looking for some general suggestions on what to check as my port rpms are jumping around a good bit. Not at idle but at running speed up to 400 rpms up and down. Starboard maybe 100 rpm fluctuations.

Not sure if injectors are all original or not but everything else seems to be. She starts great and idles fine. Also appears to be running rich and a little light on oil pressure compared to other engine.

I had my Axiom running and took a video clip of the action.

https://photos.app.goo.gl/vGFgd5Xmz81Tvy7w8

 

[370]

Also, quick mention to Allen at Fox Marine for helping get the engine gateways setup! Never would have realized the issue so quickly without the running stats.

 

[Espos4]

Does it “sound” like the engine speed is fluctuating that quickly?

It doesn’t appear to from what I heard on the video.

 

[370]

Yeah, you can hear it clearly back off as it stumbles at times. It happened before I had the stats running and I thought I had hit something. Sorry you can’t quite hear the hesitation.

 

[Espos4]

What does the maintenance history say?
How many hours one the motors?
When were the filters, plugs, wires etc last replaced?
Are any of these due for replacement soon?
Are any plug wires loose?