Yamaha 150 2-cycle idle problem

[Psalm 99]

Been running my engine about every three weeks on muffs waiting for fishing season. Engine started right up today and appeared to run smoothly, until backed off to idle. Dropped below 500 rpm and needed to be quickly throttled up to avoid shutdown. Idle was working fine before (set at about 750 rpm). Only difference is the three weeks of sitting. Full tank of non-ethanol fuel, Ring Free always added to fuel. Low hours on fuel water separator. Did this a number of times before shutting engine off. Removed cowling a checked position of idle screw (locked down in correct position, not loose). Fuel pumps have about 60 hrs since replacement. Carbs were disassembled and run thru sonic cleaner about 70 hrs ago. Thinking of running a heavy dose of Seafoam (1:6) thru carbs but appreciate any help.

[Zara Spook]

Funny the similarities here between your situation and what I experienced yesterday. 150 2-stroke myself, sitting for three weeks with Ring Free, Stabil, and non-ethanol in the tank. My tach was also reading at 500-600 at idle, rather than the customary 700-800. Wasn't shutting off, however.

The difference is that I took it out and ran it for a good while, at varied RPMs, and took it up to WOT for a couple minutes at the end of the trip. After that on the muffs (during flush) the RPMs were back at 700-800 at idle.

You may just need to get it out there and blast it.

[TownsendsFJR1300]

+100 ^^^.

If you have Ring Free already, run that at 2-3x's the recommended amount. I've used it that heavy for different engines (with running issues W/O issue).

Also, simply drain the float bowls (drain screws) and catch what comes out. I use a super clean tuna fish can but just look for any debris. A pump of the primer will push some fuel thru there flushing it too.

I use non-ethonol fuel as well, but still use a FUEL stabilizer besides Ring Free.

If the fuel smells foul, is cloudy, (bad), gotta dump it...

[Psalm 99]

Thanks Guys

All good thoughts. With a night's sleep, I'd reached just about the same conclusions: Engine needs a good running, change fuel/water filter, drain filter at engine and pump with primer new fuel thru lines. Suspect this will solve the problem this afternoon. Thanks again for the good input.

[TownsendsFJR1300]

Please post back how it goes.

[Psalm 99]

Looking Good!

Engine idle back to normal. Pretty much did as suggested:
1-- Added 8 oz of Stabil to 1 gallon of gas, shook, and emptied into tank (tank was about 95% full @ about 80+ gallons of non-ethanol fuel
2--- Drained carb bowls (6) by completely removing the drain bolts. Replaced bolts.
3--- Replaced 10 micron fuel/water separator
4--- Placed container under engine filter housing and pumped about a pint of gas thru system and into container.

Engine started right up. Let run for a few minutes and went down to idle. Idling between 600 - 700. Shut engine down and checked for any leaks. Started back up and let run a little longer at about 1800 rpm. Went back to idle which now stayed steady at between 700 - 800 which is where I set it at the beginning of last season. In retrospect, I didn't flush the gas line between the filter and bowls so I'm guessing that this is the reason the idle did not immediately respond to my setting. Engine definitely would benefit from a good ocean run. Thanks again for saving me a lot of hassle.

[bajakeith]

lack of running.......

I don't have excact number,, but So much of what I sea is lack of use,,negelt and/or abuse....And NO service and LOVE !!

[TownsendsFJR1300]

Glad it was an easy fix!!

Safe boating!!

[RayBersch]

Waiting for fishing season?

I'm sitting in Maine right now wondering why someone in Hawaii is WAITING FOR FISHING SEASON! I think I'd go out and find those suckers, no matter where they are. Sigh, oh well, the water is still hard here so I will wait for fishing season.

[TownsendsFJR1300]

I'm sitting in Maine right now wondering why someone in Hawaii is WAITING FOR FISHING SEASON! I think I'd go out and find those suckers, no matter where they are. Sigh, oh well, the water is still hard here so I will wait for fishing season.

Ice fishing????