Nissan outboard no power

[glassdad]

I have a 5hp Nissan outboard that lacks power. When not in gear, it will roar with power. When I shiift into gear, it lacks power. As we are cruising along, it will speed up some or slow down. I am using it on an inflatable dinghy carrying two people. I know that in gear any motor will run with less power than in gear but this is a LOT less. The motor is 15 to 20 years old and probably a little dirty inside.

Is there any gas treatment I can add to clean the engine or give it a little more power? Can I use higher octane gas (92) with oil added? Will that help?


Thanks for the advice.

[treilley]

Probably a dirty carb with clogged or partially clogged jets. Octane will not help. Find a new carb or rebuild the one you have. You may even be able to boost the HP beyond 5 with a carb from a higher hp motor. Some of them have common power heads and just a larger jetted carb.

[dabnis]

Before you rip the carb apart you might want to mix up about a 50% mixture
of gas and Berryman's B-12 fuel additive, or similar products like Gumout,
and run it a while. Let it sit for a day or two, try it again, you may be lucky.
After you get it fixed suggest you drain the carb if it is not going to be
used for a week or so.

Dabnis

[HDChopper]

Yes dabnis knows Berryman's B-12 products really work I really like thier carb cleaner it will strip a old carb of the crap of any kind ..

But personally I would check all berings on the lower end and see if there is any buildup of old oil that has turned to tar in the bottom , from your discription it sounds like drag from gears & shafts might be the grimlin ....

[dabnis]

Originally Posted by HDChopper

Yes dabnis knows Berryman's B-12 products really work I really like thier carb cleaner it will strip a old carb of the crap of any kind ..

But personally I would check all berings on the lower end and see if there is any buildup of old oil that has turned to tar in the bottom , from your discription it sounds like drag from gears & shafts might be the grimlin ....

Interesting possibility!! could be if the engine sat unused for many
years? IIRC, Berryman's used to say "add it to your engine oil to free
sticky valve lifters" or something like that. the current container
makes no mention of that, however. It might be a consideration for the lower unit before doing open heart surgery on it. I would contact Berryman's
first:
Part Cleaners and Degreasers

Maybe an air leak in the fuel line fittings. Many years ago on
old carbs with a whole lot of miles on them the throttle shaft to carb
housing fit could enlarge somewhat allowing a small air leak. Probably
not likely on an outboard used for recreational purposes?

Probably your ignition is OK but it wouldn't hurt to do a close visual check
on all electrical connections. A shop should be able to run a test on it.
Let us know what you find.

Dabnis

[dabnis]

Forgot this, check, and or replace any fuel filters in the system.
My Honda has one that fits into the fuel line at the tank, it is not
visible from the outside.

Dabnis

[glassdad]

I will check the filters. The engine feels like it is dirty. Sometimes running slower and then speeding up with a little more power. I am using it this weekend and will not be able to tear down the carb. Will B-12 just clean the carb or will I have to tear it down?

[dabnis]

Originally Posted by glassdad

I will check the filters. The engine feels like it is dirty. Sometimes running slower and then speeding up with a little more power. I am using it this weekend and will not be able to tear down the carb. Will B-12 just clean the carb or will I have to tear it down?

It will disolve deposits like varnish & gum that have hardened, not sure
about hard small gritty sand like debris? However it is easy to try,
nothing to lose, before ripping it apart. Let it set fir a while after you get
it running.

Dabnis

[HDChopper]

Ya shoot it in every hole you can find on a carb first it won't hurt anything , amazing stuff I use it in the bike shop before any teardown on a carb job...

Normally I will shoot down the carb real good and fill the carb bowl and let it sit for an hour or so turn on the gas and run the machine , it will burn like gas just fine ... also once started shoot some around the carb manifold to find air leaks , the eng will gain rpm's if there is a leak while doing this...

[glassdad]

I will try it. Thanks for the help.