Yamaha, Y15 SMHA 2017

by John Lawson
(Port Orchard, Washington State, USA)

Won't Idle Low For First 15 Minutes

Hi, I've got a 2017 Y15 SMHA outboard that has trouble starting (4th or 10th pull).

Once it does start, it stalls at low idle. I have to fully gas it for 15 minutes before it will be stable at low idle.

Once it warms up, it has no trouble, but if I shut down the engine and it sits for 3 hours then the issue returns, even in warm weather.

This is only really a problem because the outboard only goes into gear when it's in low idle, so I can’t even drive the darn thing while it’s warming.

Weather here in the Sound has been 50 Degrees F.

I got this outboard in March, the PO warned me the motor took some time to warm up, but this is kinda silly. Said he’d been running it all winter.

* Yes, I'm starting the outboard in the throttle starting position, and I've tried every other throttle position just for fun.
* Yes, the rumors are true; this outboard doesn't have a manual choke. No, I'm not missing it, the engine has a Yamaha Primestart system.

Things I've tried:
* Pulled and tested the Primestart valve on 12 volts. It works.
* Running 100% ethanol free gas
* Seafoam fuel system cleaner
* Replaced all fuel lines & fuel bulb
* Checked for fuel leaks - none
* Replaced inboard fuel filter and axillary racore water-fuel filter
* Carburetor rebuild * clean, complete with meticulous scrubbing & air hose blowout, jets were not blocked when I took the carb apart
* Visually checked all relevant gaskets – they look good
* Checked for Vacuum leaks - nothing
* Pulled and cleaned spark plugs, checked for gap and spark – all good
* Visual inspection of air filter – clean as a whistle
* Read every damn forum post I could find, called three mechanics, and spent days working on the darn thing
* When I store the outboard at the end of the day, I always shut off fuel and let the carb run dry

Click here to post comments

Join in and write your own page! It's easy to do. How? Simply click here to return to Yamaha Outboard Forum.