Allrighty guys and gals, seeing as how spirng is not too far away, I'm looking for some help with the ol' canoe motor. It is a Tanaka TOB-300 outboard. 3hp, great on the long floats. Problem is, it won't run for long under load. Out of the water, it will run forever at any throttle position, or at least until it runs out of gas. It will die after idling for a few minutes though. After the motor poops out while it's still cold, if you pull on the starter it will usually fire right back up. When it's warm, then it usually won't start back up. This motor is old, so old that I don't know how old it is (I'm only 18)... Basically it had been sitting in my grandmother's garage for a few years. We got it along with the canoe, and have replaced the gas tank, fuel lines, and flushed everything out. I replaced the spark plug, but I'm not sure if it was the right one that was installed to begin with. I'm thinking that a new spark plug will help fix this problem, but any other ideas?

 

CANOE and MOTOR should NEVER be used together.......get an OAR

There should be an example of a "OAR" in this picture somewhere:

 

Yeaaaah... But this canoe is made for a small motor, has the plate and everything at the back of it. It's a big 17 or 19 footer 3 man cargo hauler something or another Gruman, I think. It's about 45 years old.... And the oars are nice, but after paddling for 20something miles, you start to like the motor. And we have been known to get waaay behind schedule, so the motor helps there too.

 

well.... I would definitely see if installing the "right" spark plug will help......

 

Sounds like blockage in the carb. Check the float level. My 8 HP Johnson had that same symptom. We rebuilt the carb and it was fine.

 

If it runs good out of the water but craps out in the water you might have a crack in the water jacket. I had this happen to an Evenrude that I had. It would start and run fine until it warmed up. Then the metal in the cylinder walls would start to expand opening the crack up and sucking water into one of the cylinders. Once the water got into the cylinder the motor lost power and then would sputter to a stop. I would check for water in the cylinder when the motor starts to sputter.

Joe

 

It's not water cooled, it's air cooled. I'm thinking the spark plug should do it. The carb has been cleaned by me, so I don't know what could be blocking anything up there. Any ideas on the ignition system? I'm not very familiar with it, anything I could clean on there?

 

Zaairman....To start, I would say do a compression check. It's very possible that the cyinder or piston is worn out just enough that when there's a load on the engine, you are experiencing a "blow by" condition causing it to die out on you. A few other things to check is make sure its getting enough fuel, and easy check would be this...get a spray bottle and fill it with some fuel then when its in the water and your running, just as it starts to die, spray the fuel into the carb...if it picks up, then you have a fuel delivery problem. So either the carb is dirty or gummed up causing the restriction, the line from the tank has a restriction in it...which may be a kink, or the filter is clogged somewhere along the line. If spraying fuel in the carb doesnt help to keep it running, then its most likely and electrical problem or, like I said before, the cylinder may be suspect, which you should see in the compression check. If its been sitting around for a while a quick "flush" (whatever that means) of the carb may not do it. I would take it apart and really clean it good with some carb cleaner and compressed air. Also, as mentioned before, the float level may be off, or the float may be saturated and is actually sinking in the fuel causing a rich condition. I'm still looking for the correct spark plug that should be in it..I have a part number, but that does me no good without an NGK or Champion number. Check out the link I posted below. It has some pretty good info and real good breakdown pictures of your motor.

http://www.tanaka-usa.com/index.php?section=129


BREW

 

Thanks BREW...I've taken the carb apart fully, and sprayed it all down and such, and used the straw thing that comes with the carb cleaner to blow out the gunk in all of the holes. I have the part number too, but once again it does me no good without the numbers. I'll check later....

 

One more thing...on top of the fule tank cap, is there a little screw, which is actually the vent? Make sure that is open all the way while up and running, otherwise you will create a vacuum and the fuel will not get to the carb....Just another suggestion whil I sit here thinking about it.

Oh, and I called Tanaka to try to get thecorrect spark plug, but the guy was out..I'll try later.


BREW

 

BREW - thanks dude. I had gotten the number before, but it was at the beginning of the season last year, and every store around here was out, and I didn't want to pay the rediculuous prices from Tanaka. And the gas vent is open, like I said earlier, it can and has run for 45 mins + out of the water before, it just poops out under a load. I think that the wrong plug is in there and it is just crapping out on me. Its new (1 season), but it is probably the wrong kind...

 

Zaairman,

Being a past marine mech maybe I can help.
Being a Tanaka air cooled it has a Tecuhmse engine. Basicly a 2 cycle lawn mower or closer yet the same as on like an auger.

First, like brew said do a compression check, it should be not much less than 90#
If this engine is pretty old it may have points. If removing the flywheel shroud and find the coil,if wires run under the flywheel, it has points. They need to be replaced or at very least cleaned and gapped. Cleaning them is best done with a clean business card. Dont use a dollar, it will not work well.

Also, for cleaning the carb you will need to take it all apart, soak it in a can of carb cleaner for a good day. Use compressed air to blow out all the passages and scrape off any old scale build up.

Your problem sounds like stuff floating in the carb being picked up by the main jet. It could also be the points or more over the condenser openning when hot.

Make sure the intake gasket is in good shape and that the tank is clean with no floatys.

If you do all this and the problem persists and compression is good you need to look for air leaks.
As the engine is running spray something like WD-40 on the gasket surfaces, intake, jug, head, etc.
If a gasket is bad this may either stall the engine or cause a fluctuation in the rpms.
If all this fails and compression is good, plug is new, points are gapped and cleaned ( gap points at .020) and carb is as clean as you can get it. Most likely the carb has just gummed up beyond repair. There are small ball bearings in these carbs that have to roll back and forth to block off the high low passages for idle and high speed.
Most likely these are rusted or corroded to the point of never working again, which case a new carb is needed.
Now on the rare instance the carb has a diaphram instead of a float, then replace the diaphram, needle and the check valve in the fuel line.

One more thing to check, if this has a hook up for an external tank, it will have a small fuel pump mounted on the side. This to can be clogged and the diaphrams bad as well as bad check valves also.

Now if none of this works, then you have a bad seal on the crank which can be checked by pressurizing the crankhousing and looking for bleed down, but at that point I would just throw it away and buy another cheapy motor.

And the plug should be a J17LM or J19LM in Champion.

Sled...

 

Sled - Thanks...but as I said...I'm 18, and have NO IDEA float/bowl/diaphram is in a carb. I just knew how to take it apart and clean it out. As for the tank being clean, it is brand new. Old one had a crack, and yes, too much gunk in it. All of the fuel lines are new. There is no external fuel tank on this motor, or a hook-up for it (that I am aware of). And thanks for all of your help guys....

 

Zaairman....look at the link I gave you in my first post. It will show you a breakdown of the entire engine. It will be helpfull for you when you start taking stuff apart.


BREW

 

Zaairman

If you dont know squat beyond what you have done. Take it to a small engine shop. Dont take it to a marine repair. It will just cost you alot more.
Take it to a tecum. dealer as they should have the parts.
My best guess is that the carb is plugged and shot and would need a new one. I think they are somewhere around $50 bucks.

Good luck, Did you get your stickers made for your emblem yet? What did you go with, 280?

Sled...