help 04 25 hp 4 stroke

[Chaz2391]

i have a yamaha 2004 4 stroke 25 hp , have fuel spark and compression but cant get the thing to fire, i am marine mechanically inclined , but cannot get this thing to fire neeed ideas . have checked the sheer pin in crank/ flywheel , changed plugs and coil pack, new fuel, rebuilt carb . motor won't even fire with starting fluid ……..

[robert graham]

Maybe timing/belt is off?... Maybe a valve is stuck open?....any compression?.

[TownsendsFJR1300]

Plus one ^^^ on checking your cams and timing belt to make sure all the marks are lined up.

I couldn't find it in the parts fisch but I don't believe there is any tensioner for that belt.

I worked on F40 that ran rough at idle, the belt was off TWO notches and still ran...

[boscoe99]

How are you testing for spark? Just a spark with the plug removed or is the plug actually sparking under compression? Big difference between the two.

If the latter, then I would check for ignition timing.