Low speed running problem - 15 hp

Tom O · Mar 5, 2013

Greetings,
Last fall we fished for three days in E.WA.
The first two days the engine ran like a champ.
The third day we trailed the boat to a different lake over a bumpy dirt road.
The engine would start but not continue to run at low speed. If I could get it into gear and accelerate it ran fine until I backed to near idle where it would quit.
When we got home I played with it some (checked plugs, fuel filter) and noticed that when I squeezed the primer bulb to initially start it the bulb would not stay firm (before it was running).
Runnning it in the yard - at a fast idle it runs then coughs then runs then coughs etc.until it quits.
Your ideas are appreciated.
Tom O

Rick. · Mar 5, 2013

Re: Low speed running problem - 15 hp

What year is it? Best of luck. Rick.

64osby · Mar 5, 2013

Re: Low speed running problem - 15 hp

My take on it would be the bumpy road stirred the tank and you pulled some crud into the low speed circuit on the carb.

Time to tear the carb down and give it a good clean and rebuild. Maybe flush the tank.

KrisKastel · Mar 5, 2013

Re: Low speed running problem - 15 hp

Sounds like the carbs, if you cannot tune the screw a little, then yes you must clean them out, or use some cleaning petrol injection fluid in your system

Tom O · Mar 6, 2013

Re: Low speed running problem - 15 hp

Rick. said:
What year is it? Best of luck. Rick.

Thanks for the reply Rick. It's a 1998 model used very infrequently.

Tom O · Mar 6, 2013

Re: Low speed running problem - 15 hp

64osby said:
My take on it would be the bumpy road stirred the tank and you pulled some crud into the low speed circuit on the carb.

Time to tear the carb down and give it a good clean and rebuild. Maybe flush the tank.

Thanks for the reply. The tank shouldn't be the problem because I had cleaned it thoroughly not long ago and I have an in-line filter. But, the carb could still be the problem.

Tom O · Mar 6, 2013

Re: Low speed running problem - 15 hp

KrisKastel said:
Sounds like the carbs, if you cannot tune the screw a little, then yes you must clean them out, or use some cleaning petrol injection fluid in your system

Thanks for the reply Kris. I'm anxious to get it in the water again so I can try some adjustment before I pull the carb.

WA-Newb · Mar 6, 2013

Re: Low speed running problem - 15 hp

I had a similar problem last year...similar in the way all was fine until I trailed it home and went to flush it out.
What I "think" was the problem was there was stuff (crud) in the fuel filter / lines / floats and the trailering made it all come lose.

I also flooded the motor while trying to start it so being new that threw me for a spin as well.

Anyway after cleaning out the plugs (I think I actually replaced mine), cleaning out the carb float bowls and letting it sit awhile she ran fine again.

There is also the possibility of a bad wire somewhere that finally gave way and lost connection..my last motor had many of those and the one I just picked up may have the same thing going on he (the PO) said, doubt this is the case with yours but if see any corroded connections anywhere it's worth taking a look.

Good luck..and I am also in Western WA. but still a boat Newbie

82rude · Mar 6, 2013

Re: Low speed running problem - 15 hp

TOM when you were towing the motor did you have the hose hooked up to it?it may of come loose.go to motor disengage the hose and put it back on.i chased a similar problem years ago till something made me go to the motor and push the hose and CLICK!back in the game .even if it doesnt click take off reattach and give it a try.do at tank also.sounds too simple to be it eh?you,d be suprised how many motors ive fixed by that simple method.

Tom O · Mar 7, 2013

Re: Low speed running problem - 15 hp

Thanks WA-Newb, I haven't had time to do any more with it yet but I'll check those areas.

Tom O · Mar 7, 2013

Re: Low speed running problem - 15 hp

Thanks 82rude, I've had the lines on and off many times now - even tried a different tank with fresh fuel from a different source. I'll get it in the water again soon - I hope, and go from there.

82rude · Mar 7, 2013

Re: Low speed running problem - 15 hp

also check for hairline fractures on the coils.boy, can they cause lots of issues also.the poor running after trailering may be just a conicidence.

the machinist · Mar 7, 2013

Re: Low speed running problem - 15 hp

You might also have a crack in the plastic carburetor top, especially over the idle adjustment screw, which will allow outside air to be sucked in. Those plastic tops seem to have been a problem in the past on some of those late motors.

Low speed running problem - 15 hp

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