2001 15hp 4 stroke idoling problem

[dieselfumes]

hello all. I have a 2001 15hp 4 stroke kicker motor that wont idle smoothly. it will idol but it is rough and some times it will pop and then stall. however It will start right back up and run for a while. also, when giving it some throttle it hesitates a little. then after running at a higher speed it will sputter after letting off the throttle.

I have removed the cab. throughly cleaned it and installed a new kit. Not my 1st boat motor so I feel confident Its its installed correctly. I changed all of the fuel lines. Installed an in line filter a head of the pump. new plugs and tuned it accourding to the shop manual. however it still runs rough and burps back through the carb while trolling. I have done a lot of research and found out that they where set up lean from the factory and usaually the back kick through the carb is due to Lean fuel mixture to the engine. They say there is a mixyure screw but I am unable to locate mine or even see one in the manual. I do think it is a fuel problem because while trolling slow It will run better with the choke closed a little bit. when I took the carb a part I made sure to clean the jet ports and everything else I could find. any help is much-much appreciated. I have tuned up all of my other motors and they run perfect. except this one.. thanks again for any help...

 

[Bosunsmate]

Re: 2001 15hp 4 stroke idoling problem

Did you have a check of inlet reeds when you had the carb off? if they are damaged it will affect low speed idle/trolling and will spit back.

 

[Bosunsmate]

Re: 2001 15hp 4 stroke idoling problem

Did you have a check of inlet reeds when you had the carb off? if they are damaged it will affect low speed idle/trolling and will spit back.
Did you put wires down the carb idle channels to check they were clear?

 

[dieselfumes]

Re: 2001 15hp 4 stroke ideling problem

Re: 2001 15hp 4 stroke ideling problem

Did you have a check of inlet reeds when you had the carb off? if they are damaged it will affect low speed idle/trolling and will spit back.
Did you put wires down the carb idle channels to check they were clear?

Yeah I did make sure they where not clogged . from what I could tell everything looked good. I just tried adjusting the carb exactly how the maual says. let it run for a while so it was warm. Hooked up a tach that I just bought for smaller motors. I could get it in the rande it said 950+- in adle. but i was up and down. the engine doesnt run a constant idle at all. so I went to set the rpm in gear .( I have it in a tank full of water.) same thing. I can get it some what in range but you can tell its not smooth. I think its a fuel problem because if I pull the choke out a little it will run a little bit smoother. my sons friend has the exact motor only a year newer and it runs like a champ... thanks again for any help. Does anybody know if the fuel mixture can be adjusted on that motor

 

[dieselfumes]

Re: 2001 15hp 4 stroke idoling problem

should add that I did put a wire down to make sure they werent clogged

 

[Star]

Re: 2001 15hp 4 stroke idoling problem

You can't put wires down the idle circuit on the 4 stroke carb. they are not straight and there is a restrictor in the passage. You have to remove the carb, remove all plastic and rubber parts and soak it in a good carb cleaner. The passage you need to clean is from the idle adjustment screw across the top of the main ventury to the back side of the throtle butterfly. Once this is cleaned it will idle like a kitten!!! Be sure the gaskets ar all good when it goes back together.

 

[dieselfumes]

Re: 2001 15hp 4 stroke idoling problem

You can't put wires down the idle circuit on the 4 stroke carb. they are not straight and there is a restrictor in the passage. You have to remove the carb, remove all plastic and rubber parts and soak it in a good carb cleaner. The passage you need to clean is from the idle adjustment screw across the top of the main ventury to the back side of the throtle butterfly. Once this is cleaned it will idle like a kitten!!! Be sure the gaskets ar all good when it goes back together.

thanks for the help. I have done that a couple times. most recently over the weekend. I bought a new carb kit and soaked the carb and cleaned it before putting it back to . only thing I havent done was to pull the jets out themselves. I did remove the screws but I was unable to unscrew the one and for the life of me I couldnt figure out how the other one came out. So I took a set of tourch cleaning wires and gently made sure they where clear. I know some say never use wire but that was the only thing I could find that was small enought. then I blew it out with my air compresser and soaked over night. I installed the new kit and started the motor. tuned the rpms just like the manual says. Both at idol and in gear. I have it in a tub of water so there is a load. It runs a little better but not smooth like other ones I have seen. I thought maybe it was a problem with the location of the fuel tank. 21' boat and the tank is in the front. so I took a 3gallon tank and put it right bye the engine. runs the same. also should mention that the bulb isnt totally hard. while running. both bulbs are brand new and so is all of the fuel lines. do you think it could be the fuel pump ? it lookes good. no holes that I can see.