Tohatsu Engine Problems.

[Brian Pascoe]

I have had a M15C since new (12).It is starting to tend to bog in on accellerating from idle.I thought it was fuel problems at first.Cleaned all fuel lines and carby.Still bogs in. Took it to an outboard mecanic. Could not fault it in their test tank. All I can put it down to would be the electrics breaking down under load.It has got new plugs.Has anybody had this problem with their engines.

[krazyfisher]

you said you cleaned fuel lines and carbies, did you clean the tank?
is the fuel bulb soft?
is the fuel line soft?
how long has it been doing it for?
did you have the choke off?

[finga]

Any decent mechanic would have tested it under load in the tank.
No point in testing a bogging/breaking down problem when the motors in neutral.
The M15C is a pretty basic motor. If none of the above things Krazyfisher mentioned are evident then it still shouldn't be too hard to find the problem.
Did this problem happen all of a sudden or did it creep in gradually??

[Brian Pascoe]

Done all of the above, had no joy.No, it was not in neutral.

[BM]

If fitted with idle jets open them out 1/8-1/4 turn.

[finga]

Done all of the above, had no joy.No, it was not in neutral.
Then why couldn't they find the fault as the motor is under load if it's in the test tank, in gear and with some revs.
Doesn't matter if the water is in the test tank or the river.
how long did they run it in the tank??
More likely to be heat related problem ie coils breaking down when warm etc if BM's theories don't work.
Did the problem happen all of a sudden or gradually start happening??

[cormorant]

Check compression
Check bent prop
Check vent on tank is open and not clogged
Check bad batch of fuel
Check filter in tank
Check for carbon deposit in exhast causing restriction.
Check for sparrow necting in airbox or a bit of rag
Check float level in carby and jets
Check gearbox oil for metal and seizing gearbox
Check thermostat and engine temp.

[Roughasguts]

Might be something really simple.
Have you lowered the motor, or put more weight in the rear of the boat.
Changed your seating position. Even putting on a few pounds your self could easily effect a 15Hp.

[Brian Pascoe]

how does one check the coils etc.I have checked everything that you guys mentioned.

[finga]

How long does it take to start bogging down when your on the water??
Bung the motor in the test tank and put it in gear and rev it the same as when your on the water for the same amount of time it takes for the problem to show on the water (give it a while longer just to be on the safe side) and the problem should show up. Same conditions, same problem.
Leave the cowl etc on as well.
Or bung on a new coil and see what happens.
Just as a thought there's nothing restricting the water intake when it's hooning along is there?? This wouldn't be picked up in the tank.

I hope to problem is sorted out for you soon matey. Nothing worse then a bugger of a problem :-/

[Gilli]

To check the coil, get your multimeter and put it on ohms, then get someone to crank the motor over whilst u r testing active to earth (neutral), should get atleast 15,000ohms..another test is get an Insulation resistance meter(megga) and put it on 1000volts and test active to earth and active to all the sheath on the coil, should get between 1+M ohm to atleast 200+M ohms

[BM]

Brian,

Primary coil winding (input) to ground a few ohms typically. Coil secondary (output, or tower, or high tension lead) typically around 1000ohms or 1K ohms.

You can check this with an analogue multmeter but you would be better with a digital meter.

Cheers

[Swamp]

You could try different plugs

I don't have a Tohatsu, but a bloke at work has a fairly new 18 horse, and he was telling me that one brand of plugs had the same effect you're seeing. Sorry i can't remember the brands