Yamaha 1999 15hp engine problem

[Cyclone268]

Hey guys, first post!! wooo 8)

Anyway, i have a small 14 foot boat with a 1999 15hp yamaha pushing it. Great motor, always fired up, amazing torque. Until yesterday. Yesterday i was driving around and it just cut. It was running on a fresh tank of fuel and i couldnt get it to start again. Got towed back to the dock, and i noticed if i put it in nuetral and set the throttle pretty high i could get it to run, but any lower it would cut out/not start. Today i cleaned the fuel filter but im thinking the plugs need to be replaced because i havnt replaced them in well over 100 hours. (i know i know i shouldve, but the thought just seemed to slip my mind)

Anyway, what do you guys think could be the issue? I know quite a bit about motors (various small engines on pocket bikes, stuff like that) so i guess that will help.

Any help it much appreciated.

Thanks!

 

[yamamarinetech40]

Re: Yamaha 1999 15hp engine problem

When was the last time it was run? Is it getting spark to BOTH plugs, or just one? Need SOMETHING to go on....

 

[deejaycee_2000]

Re: Yamaha 1999 15hp engine problem

Did you make sure your ventilation screw on the fuel tank is open? .......

 

[Cyclone268]

Re: Yamaha 1999 15hp engine problem

Last time it was run was quite a few times the day before. I do use it alot. And yes the ventilaton cap is open.

 

[rodbolt]

Re: Yamaha 1999 15hp engine problem

first verify compression and spark. a compression tester at wal-mart or sears should be less than 25 dollars.
A spark tester can be purchased or home made as long as it has about a 1/2" gap.
if spark and compression are good then hunt for trash/water in the carb and fuel pump.

 

[Cyclone268]

Re: Yamaha 1999 15hp engine problem

Hmm alright, just wondering, has anyone ever made some sort of guide for looking at/cleaning the carb? ive never really had to do it before so i dont really know..

Thanks

 

[rodbolt]

Re: Yamaha 1999 15hp engine problem

yes
its called a factory shop service manual.
not like its complex but the manual is nice to have.

 

[Cyclone268]

Re: Yamaha 1999 15hp engine problem

Hm, alright sounds good. Come to think of it, ive seen a few of these for sale on ebay so ill be sure to take a look.

Thanks!

 

[Cyclone268]

Re: Yamaha 1999 15hp engine problem

Little update, the engine runs at idle, but only for a few seconds and VERY rough. So today im off to get new plugs and a compression tester. I plan on cleaning the carb to see if that has any effect.

Thanks