15HP idles up up up then stalls

[fortunate2001]

A couple of weeks ago my 15HP 2 stroke has become hard to start, and instead of idling as usual, it speeds up immediately going to high revs. Not full throttle revs, but high enough that I don't want to drop it into gear...

After 10-20 seconds of high revs, slows down and stalls. Several more pulls and full choke to get it started again.

I've been able to get it into gear and get the job done, but it is stalling consistently now when throttle is low. Docking has turned into bumper cars

Revving up means starved for fuel, right? But it runs fine once underway, so I think the tank/hose/fuel pump are all OK. Maybe the carb idle jet is fouled?

This is a new to me motor, so I haven't taken it apart yet, not sure what is involved in accessing and removing the carb for a cleaning.

Any help much appreciated!

 

[oldboat1]

Running lean for some reason. Maybe a holed fuel pump diaphragm, maybe an overly lean air/fuel mix. maybe the tank vent is closed.

Show a model number.

 

[racerone]

A 1956 / 1965 / 1983 or 2005 model ???

 

[fortunate2001]

Yes, sorry, should have said- It's a 1996 E15RED

 

[oldboat1]

You need a manual to find the initial setting for the idle needle on top of the carb (probably 3 turns open or so for a '96.) From the initial setting, you turn the needle clockwise until the engine misbehaves (stalls or lean sneezes), the set about 1/4 turn richer. I'll guess your needle is set too lean. If no change/response, the carb likely needs cleaning, especially the idle circuit at the top.

 

[fortunate2001]

I haven't touched the idle needle since it was running OK, so thinking that setting is not the cause. Could be gummed up, though. I used to pull the carb off my 9.9 all the time, bring it home to clean. The 15 looks like more than a just a couple nuts to disassemble. I guess that's next.

 

[fortunate2001]

Oldboat1 - you are correct - 3 full turns initial setting for mine. I didn't know where it was set (new to me motor), and it was bugging me, so I tightened until I thought it was fully down. I stopped after about 4 1/2 turns, Not sure I actually got all the way down, the spring on the screw was making it hard to turn, but I didn't want to overshoot and deform the needle, so I stopped there.

Anyway, backed out 3 full and started her up. Better. A few 1/8th adjustments and she was idling again.

Put a couple hours on it over the weekend, still starting and running OK.

Maybe just the act of closing and reopening that needle pushed out enough gunk to let the gas flow...

 

[oldboat1]

Glad it's better. It's a good sign that it's sensitive to small changes.