90tlrw stalling in idle after use

[DrLivingston]

Hey guys,

New to this forum and just picked up my carolina skiff that has a 98 yamaha inshore 90hp motor. 90tlrw

It has had a bunch of work done recently that I know of. Seemingly very clean spark plugs, the carbs are freshly done. Again the paperwork I got with it matches what they look like so I can say its safe to assume that.





Here is the dilemma. After running her (not even hard) for about 30 mins once I am just idling it stalls out or is very rough idle. The water stream is also weak, prob needing an impeller. It's overheated on me once already, again at idling the stream is very weak. Not sure if the issue are related. But she can't stay on idle after a ride without sounding rough or dieing out and having quite a hard time kicking back on. Any places to start looking?

As a note I am in Tampa Bay using it around the shores island hopping. Thanks guy!

[boats.net]

Run a compression test, probably need to remove and clean carbs. Need to replace water pump.

[robert graham]

Mine is a 1999 Yamaha 90C, very similar to yours....just wondering if the Linc and Sinc procedure was done on the carbs after they were cleaned?....and maybe your idle RPM is set a bit too low?...should be about 750 RPM at idle, otherwise maybe cause motor to stall?....just some ideas since you mention having carbs cleaned...by a reputable Yamaha mechanic?...

[DrLivingston]

Thanks for the replies. I was told that the previous owner himself changed water pump. So with that said I will pull it and do it again because who knows if it was even done correctly.

The carbs were serviced but I would assume he wasn't a yamaha authorized shop specifically. I am calling the shop tomorrow to ask more to the mechanic who worked on it as what was done because his cursive on the receipt rivals a 3rd graders.

I will note the idle tomorrow and see how close to that 700rpm mark she is when I get her on another water test. As far as pulling the head cover and checking water passages is there a view of one floating around of where to check as I hear there are a few pin size holes that allow water in that may be clogged, I'd like to know where I should be looking. Also I am a self funded bmwcca member racing my own cars so motor work is no stranger to me, but I noticed some silicone or putty coming out of the gaskets on the motor so when reassembling the head cover any special gasket material to use?

Thanks!

[robert graham]

While you replace the water pump, maybe inspect or replace the thermostat and pressure control valve to be sure your cooling system is fresh....good luck!