Outboard help

[brak]

I've got a little outboard that seems to misbehave - and no one locally that has a clue (and won't charge more than this thing is worth)

It's a single-cilinder 4 stroke Nissan. It seems to have a problem idling or staying in low RPM.

1. When under load, it will often shut down at RPM under the "low speed" marker (which is not good because at marker it's pushing my boat > 3kts).

2. When shifting into idle, even at low throttle, it will rev up like hell, sounds like a little crappy jet taking off.

3. From 1 and 2 - very difficult to use it for docking and close quarters movement, it will jump when put into gear, then shut down etc.

I tried:
- changing oil
- changing the lonely spark plug
- playing with a throttle/idle adjuster/whatever that's called

My knowledge of outboards ends right there. Ideas and help would be appreciated.

[SlowButSteady]

Sticky throttle linkage? Dirty carb? Gremlins?

[poopdeckpappy]

Check low speed jet ( or slow jet ) and have the igniter checked, they have problems with them, if it's inside a couple yrs old, Nissan should replace it

[labatt]

Ditto on the low speed jet... and gunk in the carb. We just had an issue with our outboard where it turns out the external fuel tank delaminated (most likely from the Bahamanian sun) and was shooting a gummy substance all the way through the fuel system. After three carb rebuilds (my wife did these) we ended up just replacing the carb and all the fuel lines from the tank through the outboard and to the carb.

[DulceSuerna]

Remove the carb, dissasemble it, put it in the gallon of gunk carb cleaner overnight, throw out the motor, buy a honda ,
JK I had the same issue with my Honda, it was junk in the carb. The jets in those little 4 strokes are TINY, clean it out, blow it out, use cleaner and small wire,
Also, if you need to leave it sit for more then a month its best to drain the fuel from the carb.

[LakeSuperiorGeezer]

Originally Posted by DulceSuerna

Remove the carb, disassemble it, put it in the gallon of gunk carb cleaner overnight, ... it was junk in the carb. The jets in those little 4 strokes are TINY, clean it out, blow it out, use cleaner and small wire,
Also, if you need to leave it sit for more then a month its best to drain the fuel from the carb.

If the motor suddenly developed the idle problem, then I believe it is most likely junk in the fuel. If you bought the outboard used with the problem, then it's probably the idle jet and dirt because someone tried to fix the problem by adjusting the idle jet. The only time I have adjusted the main and idle jets is going to a lake at 10,000 feet elevation. If there are no plastic parts, I have used lacquer thinner, but be careful around flames and light bulbs, or even dragging a metal pan across rocks with lacquer thinner because it is easy to ignite. Also, light bulbs have started many a gasoline fire while working on fuel tanks, especially if you break the bulb with fuel around on things. For blowing out parts, I have used those cans for blowing dirt out of keyboards and computers if no compressed air is available. Be very careful with the small wire as you do not want to enlarge any orifice. The fuel tank probably has junk in it so clean it out also. Maybe you could even fit a small fuel filter on the fuel line. Be careful taking the carb apart because on some there are little metal balls that are used as valves. If one bounces out, you do not know which passage way it came from. Draining the carb is good if easily done. Otherwise, I turn the fuel off with the engine running and tied to the dock. Let it run out and you will find very little fuel left in the carb bowel.

[brak]

Thanks guys. So the general agreement seems to be "dirty carb". Now, since I have no clue - could someone provide slightly more detailed instructions?

I.e.:
1. Where is the carb? Is it the part on top of the main engine where throttle control connects (and that seems to have a little air intake)?

2. Does cleaning it mean I need to take it off completely and apart?

3. Any other clues (or, may be, a photo of what taking off the carb looks like)?

4. What is "low speed jet" and where is it located?

BTW I always run the fuel out (i.e. disconnect the hose and let the motor run out) after motoring. I guess it didn't help.

[mattstamour]

Dude,
I feel your pain. Learning is expensive.

You may be able to google up a copy of the parts manual for your model that gives you a blow up with each part listed. That helped me gain the confidence to work on an old Johnson I had.

[brak]

I have a parts manual, but it's not entirely convenient to use for identifying things unless I already know what I am looking for. Which is why I am here

As an aside, I guess part of the issue is that I just don't like engines. I usually take anything mechanical or electronic apart easily and (most of the time) can put it back together too. With engines there is just this feeling that I don't want to do it - and they make little sense to me. No one can help with that

[dabnis]

Brak,

Before ripping the carb apart try mixing a carb cleaner,
such as Berryman's B-12 fuel additive, at about 50% with
gas and run the motor at all speeds for a while. Let it set,
without draining the carb, for a few says or so. Then run it
again with the same mixture. You may get lucky without
having to pull the carb apart. If not, be really careful when
taking it apart. Suggest working over a large clean towel.
Also, check for any possible air leaks at fuel line connections.

Dabnis