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Old 03 November 2013, 15:10   #31
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I left this in the garage unit I had time to look at it again. Stripped the carb (again) 2 weeks ago and it's been sitting in solvent for 10 days, reassembled today and the fooker is just as before, double bollocús.

Really beyond me, been through everything, just need to get it fixed somehow so I can move it on. The legendary Tohatsu 9.8 has never lived up to its reputation for me...
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Old 03 November 2013, 15:22   #32
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Have you adjusted the carb idle screw? Try one full turn from fully seated for starters and see if it improves. What about the fuel pump? Diaphragm kits for Tohatsu are excellent quality.

Once you rule out fuel, I'd take a closer look at the HT leads.
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Old 04 November 2013, 07:34   #33
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Thanks Spartacus, I will look at that. The fuel pump diaphragm looked fine but will look again, do you have a link for the kits?
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Old 04 November 2013, 11:23   #34
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Max

We a have seen a large number issues with engines like yours in the last two years -far more than we used to see in the past.

Your problem is almost certainly "gunging up" and contamination of the fuel caused by the ethanol "bio-fuel additive" in your fuel.
This additive is now added to all the petrol sold in the UK and EU (the USA doesn't have that problem). Basically if the old petrol fuel goes stale in the carbs, the biofuel additive will form a very thin film on all the jets, inside carb surfaces etc etc

Stale fuel now happens a lot quicker than it used to. The additive makes no difference in cars, because most cars are used regularly- however marine engines often sit idle for months at a time. We have seen cases of engines left with stale fuel going off in just 6-8 weeks, (not 6-8 months that it used to take for fuel to go off)

Whilst you have obviously cleaned most of the insides of your engine, my suspicion would be "bio-gunge" remains either inside the carbs or especially stuck to the jets and inside the jet passages. Quite possibly there are also issues in the rest of the fuel system.

In and around the jets, the bio-fuel is very sticky and you will find it is a lot more difficult to clean off than the "old" petrol used to be.

If you get really stuck, please give our workshop manager Andy a call on 01756 792335. He is pretty good at diagnosing these issues.

Peter Bryson - Pennine Marine
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Old 04 November 2013, 11:47   #35
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My Tohatsu 3.5 did the same and my mechanic said exactly the same as you
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Old 04 November 2013, 11:51   #36
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Peter Bryson, would you recommend running an engine like this with the fuel supply removed - until it cuts out - as a prevention measure? I always do this with mine and so far so good.
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Old 04 November 2013, 12:05   #37
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Quote:
Originally Posted by willk View Post
Peter Bryson, would you recommend running an engine like this with the fuel supply removed - until it cuts out - as a prevention measure? I always do this with mine and so far so good.
That's what I was advised to do willk and also pull the choke out to empty the carb.
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Old 05 November 2013, 08:52   #38
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Originally Posted by willk View Post
Peter Bryson, would you recommend running an engine like this with the fuel supply removed - until it cuts out - as a prevention measure? I always do this with mine and so far so good.

Yes - definitely a good idea to disconnect the fuel and let it run out on idle. Also a very good idea to take all your old fuel from the tank(s) and use it in the car or lawnmower in order to start fresh with new fuel at the start of the season.

This biofuel gunk is a nightmare to get rid of using the traditional techniques of cleaners airline etc

regards Peter Bryson
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Old 05 November 2013, 09:23   #39
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Peter, sorry for the delay in replying but wanted to check my memory after seeing your post and believe it or not the engine has always had a 'Penine Marine, Skipton, N. Yorks' service/sales sticker on the top of the hood!

I am pretty carful about fuel and it was new fuel in the engine for sure for the Devon holiday when the issue started, just to repost from my OP:

---------------------------------

"Been on the River Dart this last week - engine has been running fine all summer until this week. After the first day's pootling on the river at 5 kts or so it started cutting out at idle/taken out of gear towards the end of the day. Got slightly worse for the next two days and was a real PITA when trying to manouver in the harbour as each time into neutral or if trying to go dead slow it died. Out to sea at other rev ranges or WOT it was fine and got full power.
Cleaned carb about 15 hours ago and it was spotless anyway, new plugs then too.
I checked plugs after issues above and they did not look too oily but cleaned them to no affect.
Just had it in water bucket and the same again, will not happily idle below about 1400, drop it to less and then 1200 and it gradually gets rougher and rougher, more erratic, slows and dies."

-------------------------------

The trolling definitely seems to be to blame.

Sadly you are a million miles from me now - any more advice you can offer with your experience?
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Old 05 November 2013, 12:15   #40
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Hi Peter, that is very kind of you, I will do that.
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