25HP 4 Stroke Wont Rev Up

[Geezer45]

Could you some help please. I have a 10/99 25 HP 4 stroke (F25ELHY) that barely idles. When I try to rev it up it dies. It appears the bottom cylinder is firing very weak or sometimes not at all. I changed the plug and that seemed to help a little but no much.

Is there a test I can run on the coil to see if it is bad?

Any other basic ignition tests I can accomplish with an ohm meter?

thanks, appreciate the help.

Old Geezer

[boats.net]

Your service manual does have resistance for ignition coil but need to check peak output voltage of stator and CDI first with a peak reading voltmeter to see if within specs.

[Geezer45]

ok and thanks. I see two leads form the coil and I put my ohm meter across them and it is practically a dead short.

Problem is no manual. I have searched for a service manual and no soap, tried google and e-bay. Do you have a source to recommend? I have a F25ELHY 10/99

thanks

[Simoncpr4]

Electronic manual

If you're UK based get in touch with Liverpool Power Boats, they sorted me out with manuals for my FT25.

Coils will be a very low resistance. If the engine is idling but won't advance when the throttle is opened then I'd be looking at timing first and then carbs.