Tohastsu 50 running on 2Cyl

[al40]

I have a Tohatsu 50 2-stroke ELPTO (oil inject) which I got at the start of the year. During run in I was running iwth pre-mix 50:1 in the tank as per instruction. It ran great and never showed any signs of oiling up.

I am now passed the run-in stage and running on raw fuel in tanks (actually a very small amount of oil something like 200:1). Starting from cold it will run fine but if I cruse at 4000-4500RPM for a while say 1hr then open to WOT, it will run really badly on 2-3 cylinders then eventually after 5-10 mins of missing on 1 cyl, run on all 3. I have replaced the plugs twice and it helps for a little while but it always seems to come back. I think the bottom plug looked more oily than the top 2 but can't verify that until I'm back down at the boat.

Any thoughts on what this could be? My experience of oiled plugs has normally been the engine won't idle but will run under load. Does this sound like a dirty carb or unbalanced carbs? I've got a good fuel filter / water seperator inline so fule going into engine should be clean.

[codprawn]

How much opil is it going through? Maybe the oil injection is pushing too much through???

[al40]

Originally Posted by codprawn

How much opil is it going through? Maybe the oil injection is pushing too much through???

Hi, I estimate I went approx 140 miles before the oil buzzer went off. At just under 1litre per mile, call it 110 litres of fuel.

At 50:1, that's 2.2L oil used, at 100:1, 1.1L of oil

Actual mixture would be somewhere between the two.

I think the oil tank is 2L and it certainly took less than that to fill it to the top after the buzzer went off.

I assume this means it's not putting in too much oil. In any case, it seemed fine when I was running it 50:1 pre-mix plus the oil inj qty taking it to 25:1 at WOT.

[al40]

Been thinking a bit more about this.

Does this sound electrical or carb related? I'm assuming electrical which leads me to:

(1) Fouled plugs
(2) faulty coil / ignition

IF it's fouled plugs, would I see these symptoms or would fouled plug(s) not make it harder to start? Do fouled plugs impede high end perf rather than low end?

I guess fouled plugs could be caused by faulty thermostat (engine running too cool), incorrect carb mixture or incorrect oil ratio. As per previous post, I don't think it's oil related so could be mixture (but I hope not as engine is new and idles perfectly). I'll check temp next time I run engine.

Could this be a faulty coil? Would a faulty coil not cause issues all the time rather than intermittent? Is a primary / secondary resitance test enough to test the condition of the coil?

Anyone any other thoughts on what I should look for?

[Biggles]

Al,

I had some problems with a Tohatsu which I bought from new. Although totally unrelated it was pointed out to me when I needed some warranty work done at 18 months that I should have had the engine serviced when it had been run in. Luckily Tohatsu never followed that bit up.
The dealer that sold me the boat never pointed out I needed that early service. I just got it done at 1 year and it was never pointed out then.
Of the various engines I've had I can't remember ever getting a service type book with pages you stamp like a car service book. Do any of the manufacturers do that ?

[Biggles]

And if its only 8 months old I'd get it back to the dealer.

[al40]

Originally Posted by Biggles

And if its only 8 months old I'd get it back to the dealer.

Yip, spoke to the folks I bought it from today but unfortunately they are in South of England and I'm in Scotland so I can't return it easily.

Not sure if I can get it looked at under warranty by local repair shop or not, awaiting contact details for Tohatsu from the dealer.

My book claims the 10hr service is a user service (just change gear oil) but annual should be carried out by dealer.

[Biggles]

You'd think that the dealer you bought it off could sort out the warranty work. Or did you buy it down south ?

Thats the major problem with these boats. I quite like the look of Humbers, but I don't want to travel up to Hull every time I have a problem. It was bad enough with my last boat going to London and thats only 50 miles. All because it had to go back to where I bought it from to satisfy the terms of the warranty.

I'm looking at a RIBCRAFT and thats a 2 1/2 hour journey. I'm hoping that all the good things said about them measn they are real well built. And if I choose a Yamaha or Suzuki engine I can get any warranty work done nearer home.

[al40]

Yes, I ordered it from a guy down south (mail order) so it's not practical to send it back - even removing it from the boat is too much work in itself. The local repair shop is based right where I keep the boat and I could just drop off the keys! These engines are not complicated so there shouldn't be a problem, it just depends how fussy tohatsu are about warranty work.

I'm happy to do some diagnostics, I just want the thing to run properly. It's a great engine when it works, quiet and smooth. I guess there is always a risk buying stuff remotely!

[bedajim]

Hi



I had a similar problem but sorted by using quick silver oil as recommended by my dealer



Have a look here you may find a dealer close by



http://www.tohatsu-uk.net/Dealers/scotland.htm



James