2004 Nissan 15hp NO POWER

[seachicken]

Have a 15hp Nissan fourstroke outboard that crapped out on me yesterday morning. It will still run but woulnt put out the power it should. It seems like its bogging down or misfireing on one cyl. It has very few hours on it and removed the carb and cleaned it well, as well as removed all the fuel from the system (thought it was just bad gas). When trouble shooting both cylinders are getting fuel and both pulgs have been replced and gapped correctly and coils are putting off good arc, but cant determine what the issue could be? It looks to be a timing problem, but havnt the slightest clue how the timing works on this motor. any suggestions?

 

[pvanv]

Re: 2004 Nissan 15hp NO POWER

You need a methodical approach to this. Manuals will definitely come in handy here, especially if you want to check/set timing. The parts catalog is available at http://www.internetoutboards.com/PartsCatalogMenu.htm. The service manual is available at any Tohatsu/Nissan dealer.

Did this problem start all at once, or was it a gradual degradation? Does it idle OK? Is it Ok up to about 2,000-3,000 RPM? Does the warning lamp come on at all?

I would start by verifying that you gave known good, fresh gas. Ethanol in the gas causes a lot more problems than expected. Double-check that main jet in the carb, and verify the fuel filter is good, or just replace it. I would also check to make sure that the crankcase oil is not overfilled -- not even one cc high. And of course verify that the cooling telltale is flowing. This motor has a "limp-in" mode. If it detects a problem (such as low oil pressure), limp-in mode will allow it to run to get you home, but will prevent full power by alternately firing the ignition as you try to increase speed. Does that sound like what you're experiencing?

It's doubtful that the timing belt jumped a notch, but you can check the cam timing marks by removing the cover over the timing belt. Likewise doubtful -- seldom a problem under 300 hours, but possible, if it was a gradual degradation of performance -- the valve lash could be a little too loose.

BUT... Most likely is that the ECU (the CD unit) is going into "limp-in" mode. If that's the case, and IF there's no actual problem to require limp-in (good oil pressure, etc.), then you have either a sensor problem (oil pressure switch -- lamp should be on if low oil pressure is detected), or an ECU problem. If so, it's probably best to get it to your dealer, before you start just swapping expensive parts.