Tohastsu 50 running on 2Cyl

al40 · 15 August 2006, 11:03

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 · 15 August 2006, 13:13

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

al40 · 15 August 2006, 13:22

Quote:

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 · 17 August 2006, 15:44

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 · 17 August 2006, 15:54

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 · 17 August 2006, 15:55

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

al40 · 17 August 2006, 19:55

Quote:

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 · 17 August 2006, 20:20

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 · 17 August 2006, 23:10

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 · 18 August 2006, 07:07

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

al40 · 18 August 2006, 12:43

Quote:

Originally Posted by bedajim

Hi

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

Interesting - I started to get the problems when I swicthed from Yamalube to Quicksilver in the pre-mix when running it in. I've since chaged back to Yamalube and prob is still there so I don't think it was related.

Yes, I looked at Scotland dealer list. I think Dundee is the closest that offers servicing so it's still a bit of a trek towing the boat. I need to call Tohatsu when I get a chance!

Biggles · 18 August 2006, 12:53

I was once told you should never mix or change the 2 stroke oils.

bedajim · 18 August 2006, 13:36

Quote:

Originally Posted by Biggles

I was once told you should never mix or change the 2 stroke oils.

I'd agree with the mixing of oils and have been told the same, but not sure how changing the oils would cause a problem

Biggles · 18 August 2006, 13:51

Was the Quicksilver oil for pre lube systems ?

I think you get different sorts of Quicksilver 2 stroke oil.

My mates Yam auto lube wouldn't take my bog standard 2 stroke Quicksilver oil.

yoyo · 18 August 2006, 21:19

I run my Tohatsu 50 elpto on quicksilver 2 stroke oil, as its "first fill" was supplied by my dealer. It has always run perfectly smooth. In fact I have been totally impressed with the motor from day one.

I believe that I have read in the user manual somewhere that it is not a good idea to switch your oil types.

al40 · 19 August 2006, 16:58

Yip I'd heard before on various forums that mixing was not recommended. Befire trying the yamalube, I asked the guys in the local repair shop about mixing oils and was told not to mix synyhetic with other types. The quicksilver premium plus (which is what I was using) is supposed to mix fine with yamalube.

I'm currently running 100% yamalube as it seems to burn a bit cleaner (less smoke when I was running it oily during run-in) and it's been running on that for at least 1 full oil reservour full.

The problem still seems to come and go so I do not belive it's related to the type of oil. I'm more suspicious of the thermostat or other elctrical issue (faulty coil).