1993 yamaha 250 outboard help

[luckdog0429]

I have a 93 yamaha 250, for the most part its a great motor, but I have a problem when accelerating slowly from idle to cruise rpm. The motor coughs and hesitates, almost like a stuttering effect and its hard to cruise in the lower rpm. It idles fine and anything over 3500 is good up to 5000, its under 3500 where this happens. Any suggestions?

 

[Salty Dog]

Re: 1993 yamaha 250 outboard help

Might be the carbs

 

[rodbolt]

Re: 1993 yamaha 250 outboard help

I would start with a link and sync.
draw back is this is one of the hardest and most complex engines to do this on.
also check TPS voltages and thermosensor outputs.
this engine uses "smart" carbs and the ECU can alter fuel enrichment based on inputs from the TPS,Knock sensor and thermosensor.
normally a cough indicates its lean for whatever reason.
could be varnish or gum in the carb circuits,could be misadjusted carb linkage. could be a few things.
start with the basics first.
you could have the cleanest carbs and the best electrical inputs but if the shutters are not correctly synchronized, guess what?
basics first then troubleshoot.
usually makes it go faster with less parts money involved.