2001 F115 ISC idle speed control valve stickig

theoldwizard1

Petty Officer 1st Class
Joined
Feb 25, 2014
Messages
341
Last year I got the valve working by soaking in a can of carb cleaner overnight. It was working fine early this summer but now I am at the lake and it is sticking again. Any sure fire cure short of a replacement ? Genuine Yamaha part is crazy expensive. Others are available.

I am pretty sure this is part 68V-1312A-00-00 is used on other Yamaha engines.
 

Cplsteve

Cadet
Joined
Aug 22, 2021
Messages
13
So I think my isc valve is bad but wanted a second opinion. Boat starts up and idles fine for about 7-8 minutes then a starts to stumble for a few seconds and dies. Starts right back up. Once running I go to give it throttle abs it just stumbles and dies out. I ran the yds on it tonight and after starting the isc went to 65 then jumped to 55-90-100 and back down to 40 and finally leveled off at 0. Motor ran and started stumbling and died. Here is a shot of the yds screen 29B5EDD9-ED70-4BD0-AD47-20B7F375794B.jpeg
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
what you see on YDS is the request, it does not know if the ISC moves or not.

do you hear the ISC rattle, resetting to 100% for next start up when you turn off the motor?

if you hear it rattle then it is moving

Yamaha recommends replacing instead of trying to clean it.
it can overheat the driver and cause ECU to need replacing
 

Cplsteve

Cadet
Joined
Aug 22, 2021
Messages
13
Yes when I shut the motor off it rattles. When I turn the key on I can hear the high pressure pump kick on for a little like to prime. So what would explain the fuel pressure dropping down to the point it stalls out. When running the boat on the water or the motor in a test tank, I can put it in gear, after about 7-8 minutes it starts to run rough and stalls with the fuel psi at 10. Also while in gear if given any throttle it runs rough stumbles and dies.

what you see on YDS is the request, it does not know if the ISC moves or not.

do you hear the ISC rattle, resetting to 100% for next start up when you turn off the motor?

if you hear it rattle then it is moving

Yamaha recommends replacing instead of trying to clean it.
it can overheat the driver and cause ECU to need replacing
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
are you talking about the rail pressure dropping to 10psi?
if so either the VST is running out of fuel so the pump in there cannot pump anymore, the VST filter/screen is plugged up, or the pump is not running.
does pumping the primer bulb help any to keep it running?
if it does not then it should not be a VST low-level problem.
 

Cplsteve

Cadet
Joined
Aug 22, 2021
Messages
13
Yes the rail pressure is dropping down to 10 psi when running. I’m guessing the pump from Amazon probably isn’t working. Is it worth getting the OEM pump for this motor?
 
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