Low Idle speed question

[Halfhitch]

I have two 115hp four stroke Yamahas. 2003 year model. Both motors start up fine but want to idle at 600 rpm. The Yamaha specs call for 750(50+ or -). Not a huge deal except that when cold at start-up when launching and manuevering to the dock, the port engine will occasionally die. It starts right back up but I'm sure if it was clicking just a little faster that wouldn't happen. Each engine has just over 1000 hrs.
I haven't checked fuel pressures yet. I'm just wondering if, on reading those symptoms, what would be your first guess about to investigate to get the idle where Yamaha says it belongs?

 

[wspitler]

I’d get the Ydis software and cable to troubleshoot. Not expensive. Look for TPS (throttle position sensor) setting/voltage. If this started all at once or over time, look at rigging as well. The YDIS can tell you a lot and test several components. Not likely to be a major issue on both engines, did they both show the lower idle at the same time? If they run good at higher power, not likely fuel.

 

[Halfhitch]

Thanks for that Bill. They have been that way since I bought the boat. I see in the paperwork that the previous owner had the injectors cleaned and a couple replaced at one time, but it was several years back. Both engines run good from idle on up. It's just the idle itself.

 

[Ekea]

do those engines have idle air control valves?