Tohatsu one step away from being an anchor!

[spartacus]

Got up at 5.00am to launch out of Cruden Bay. Picked up my brother on route and we were on the water by 7.30am. The sea was calm which is a first for the east coast!

I have an issue with the main engine. I had a oil recirculation pipe blow off in April (first trip out in April). Thinking it was carb related I'd striped them the previous week. The engine is a 2006 Tohatsu 60hp, 2-stroke. The carbs were clean as a whistle, no deposits, etc. Fuel was fresh. It's an autolube engine (Quicksilver topped up).

I also renewed the primer bulb after that first outing with a Quicksilver replacement, as the original rubber bulb was hard.

Not far out of the harbour after launching - the engine felt bogged down. Normally the Tohatsu is eager and quick to respond, but it was very sluggish. I'd reset the fuel pilot screws on the carbs to 1 5/8 turns from lightly seated, but it was struggling. After various impromptu stops it ended up at a full 4 1/2 turns out, which is crazy.

The engine pumps water fine. The impeller was changed last season. I also renewed the fuel pump diaphragm, thermostat, last year, etc. All genuine Tohatsu parts, etc. The head gasket spark plug holes had threaded at the start of the season, so I had them retapped (steel inserts) and used a new gasket. No indication that the gasket has failed.

The spark plugs are from last year. I changed them to another set I had on board and it did seem to make a difference. I'll try changing the sparks, but wondered if anyone has any other suggestions. Can the timing go off, or could this be a weak spark from one of the HT leads?

With two-up we topped out at 27mph which is poor. It normally does well over 30mph and the power delivery is instant and smooth.

Earlier thread here for info: http://www.rib.net/forum/f36/tohatsu...ugh-56135.html

[pow2gran]

I have the same engine and ended up having the fuel pump replaced after repeated loss of power. The pump is apparently similar to other outboards and the engineer put a used Yamaha pump on. Not looked back!

[spartacus]

Originally Posted by pow2gran

I have the same engine and ended up having the fuel pump replaced after repeated loss of power. The pump is apparently similar to other outboards and the engineer put a used Yamaha pump on. Not looked back!

Interesting, thank you for the response. I rebuilt the fuel pump last year with genuine Tohatsu diaphragm parts last year. I'll strip it down and check it again.

How did the issue manifest itself with you? Did it happen all of a sudden, or prolonged issues?

How many turns out from lightly seated are your carb pilot screws - 2 full turns?

[Roflhat]

the fuel pump on my tohatsu 50 is rubbish as well, I've got a replacement Mikuni one to go on, comes standard on seadoo/yamaha jetskis

[spartacus]

Cheers Roflhat.

I'm going to check compression on all the cylinders before throwing yet more money at this problem.

[henryfreston]

Originally Posted by spartacus

Cheers Roflhat.

I'm going to check compression on all the cylinders before throwing yet more money at this problem.

friend of mine had similar symptoms with a 100hp yam 4 stroke. It turned out to be the HT leads & coils- he replaced both at same time so not sure which resolved the problem.

[spartacus]

Cheers Henry.

I'm inclined to think its electric rather than fuel. Last year I renewed the inline fuel water separator, cleaned the fuel filter on the side of the engine, rebuilt the fuel pump (genuine Tohatsu parts/diaphragms), and just replaced the fuel primer bulb to Quicksilver part. All the fuel hoses are in excellent condition and I've checked the connectors, etc. The carbs have been rebuilt countless times, and are spotless. Fuel was new and oil is from Autolube reservoir. Butterfly choke valve was seized last year with a little corrosion, but it moves freely.

Electric wise, I've just order new NGK spark plugs. The battery was on trickle charge the day before we went out. I tested it tonight and it's reading 12.4v. The HT lead and coil pack (3F3-06040-0) are a £70 part plus shipping. They do come up on Ebay from time to time, but given its difficult to test that could be false economy? Is there any way to test them. I have a multimeter but I assume they require something a little more sophisticated?

Not sure if it's related, but the tachometer is on the blink too. I know the green wire is the pulse signal. Could be something or nothing?

[henryfreston]

Originally Posted by spartacus

I'm inclined to think its electric rather than fuel Henry. Last year I renewed the inline fuel water separator, cleaned the fuel filter on the side of the engine, rebuilt the fuel pump (genuine Tohatsu parts/diaphragms), and just replaced the fuel primer bulb to Quicksilver part. All the fuel hoses are in excellent condition and I've checked the connectors, etc. The carbs have been rebuilt countless times, and are spotless. Fuel was new and oil is from Autolube reservoir. Butterfly choke valve was seized last year with a little corrosion, but it moves freely.

Electric wise, I've just order new NGK spark plugs. The battery was on trickle charge the day before we went out. I tested it tonight and it's reading 12.4v. The HT lead and coil pack (3F3-06040-0) are a £70 part plus shipping. They do come up on Ebay from time to time, but given its difficult to test that could be false economy?

Not sure if it's related, but the tachometer is on the blink too. I know the green wire is the pulse signal. Could be something or nothing?

one way you can test if it is the ht leads is to spray some WD-40 (what we did to diagnose my mates dad's problem) if you see some improvement then it would indicate it could be the HT leads.

I mean at the end of the day is £70 and the engine may benefit from new ones anyway because everything needs replacing eventually.

[A1an]

I might be barking up the wrong tree here BUT, doesn't the tacho signal come from the charge coil on the stator?

Have you checked output voltage whilst engine is running?

[henryfreston]

Originally Posted by A1an

I might be barking up the wrong tree here BUT, doesn't the tacho signal come from the charge coil on the stator?

think we may have found the problem

get that ht kit ordered

(assuming A1an is right then everything makes sense )

[A1an]

Originally Posted by henryfreston

think we may have found the problem

get that ht kit ordered

(assuming A1an is right then everything makes sense )

I wouldn't order anything before doing more fault finding.

[henryfreston]

Originally Posted by A1an

I wouldn't order anything before doing more fault finding.

but its pretty clear its not fuel, similar symptoms to the case i mentioned and now the tacho isn't working properly- seems like a no brainer to me? I mean £70 is two tanks of petrol at the end of the day.

[A1an]

Originally Posted by henryfreston

but its pretty clear its not fuel, similar symptoms to the case i mentioned and now the tacho isn't working properly- seems like a no brainer to me? I mean £70 is two tanks of petrol at the end of the day.

I'm talking about the charge coil under flywheel, NOT the ignition coil that your HT lead comes from.

[henryfreston]

Originally Posted by A1an

I'm talking about the charge coil under flywheel, NOT the ignition coil that your HT lead comes from.

sorry I got the wrong end of the stick

[spartacus]

Thanks Alan, you might just have nailed it.

Here's the part list. Anything here jump out and how do I go about testing the little blighter!

[A1an]

Hmmm... electrics aren't really my thing dude, I get the basics and looking at them in situ on an engine I can usually get by but usually by trial and error!

First step I would do is get the engine running and check battery voltage, 12.8v ish with engine off, 14.4v ish with fast idle. Some modern engines will charge at idle, some need a fast idle.

I don't know if your tacho issue and power issue are one and the same but who knows.

When did tacho pack up?

Same time as engine problem?

[spartacus]

Yes, electrics aren't my thing either! It's a good call though.

The tacho has been intermittent. I had an issue with Tohatsu wiring last year. Someone should tell Tohatsu to use tinned cable when making outboards!

I rewired part of the outboard cable loom last year (corroded wiring) and checked continuity through all the wires to the remote. I could check the green pulse wire for continuity to the tacho again at the weekend. The tacho illuminates, but that's about it. Last year the overheat or low oil alarm sounded and strangely it did this on Sunday too, for a very short burst when starting the engine. If it's low oil the oil lamp on the tacho should illuminate.

The engine is an autolube and it's definitely using oil as I check the fill line. When it sounded last year I added a little more oil to the petrol tank rather than risk a seized engine. Call it cautionary, but better safe than sorry.

It pumps water and the tell-tale is very strong. The impeller was changed last year, and I renewed the thermostat, again a genuine Tohatsu part. I also had to renew the head gasket (stripped spark plug threads on number 1 and 2 cylinders), so a good opportunity to see water cooling passages. I cleaned it all up and reassembled.

I can't see this being a rev limiter or faulty sensor issue. As far as I'm aware the Tohatsu is a fairly agricultural bit of kit, with an overheat sensor on the block and an oil level sensor on the oil reservoir. If the rev limiter was introduced I'd be reduced to 3,500rpm. At the weekend I clocked 27mph on the GPS at wide open throttle (albeit bogged down) so I know it's not that.

I'm slowly rebuilding this engine one part at a time!

[RIB-Teccie]

May be a bit late in the day but there are some other simple steps to see what is wrong.

1) run engine with a spark checker installed.

2) back off fuel pump from block and squeeze bulb. If petrol comes out of the middle hole, it's the fuel pump.

3) at the same time look around carbs for petrol coming out of breathers, if it does it is the float needle or height.

4) remove airbox and launch boat. Run engine in gear at speed and look down the venturi, if you have a fuel blockage to will see it straight away and which carb.

5) replace airbox and undo the loom whilst running, that will tell you if it is the control box.

6) I assume fuel system to engine is A1

7) many electrical problems are intermittent. Whatever the problem with your engine, it is always there so should be findable.

8) I was never convinced by plug inserts, if you cannot find anything else wrong, it may be back to square 1

[RIB-Teccie]

These are the spark checkers I was talking about.

[Locozodiac]

Spartacus,

Would be wise to invest on a service manual, flywheel coil is the party soul, if altered, you'll start to have all sorts of electrical failures down the road > CD > Ignition Coils. It's easy to check, need an appropriate meter, just disconnect cables connect to meter and crank engine and check achieved readings, compare to factory ones.

But if having heat related intermittent issues, that's another story. Btw, you have 3 spare ignition coils or a 3 sole unit, assume CD is independent too ?

Adjust back idle carb screws to their original settings, only works at idle, at any other throttle setting than idle, fuel/air mixture is fixed and non adjustable.

Happy Boating