Engine very hard to start after returning home!

Mattster · 05 September 2021, 21:29

Tohatsu 6hp 4s, 15 hours from new.

OK, so this has happened on the last two outings now, the most recent being today.
When I get back from a day on the water and go to flush the engine, it is incredibly hard to start, bordering on impossible. The last time I tried, it took perhaps 15 minutes of pulling, messing around with choke etc before my neighbour finally got it going. Today, the same - except I couldn't get it going at all. I came back to it two hours later, after having been held upright on its stand, and it started first pull (no choke).

So, what is going on here?

In general, I have had no issues starting this motor either at beginning of day, or during the day (probably stopped/started it 30 odd times today when drift fishing, always first or second pull).

When I get home, of course the engine has been on its side for perhaps an hour, after which I put it on its stand and, typically, probably leave it half an hour or so at least whilst I sort out other things. When I go to start it, I do the usual things; connect to tank, open the air vent, pump the bulb. Initially I try without choke, thinking it might still be warm, but then try basically everything and still no dice.

I know less than I should about engines, but does this suggest that perhaps it is flooding when on its side and needs to dry out? I only seem to get this problem at the end of the day, not at the start - although of course the engine has been stored on its side on the way to launch.

If anyone has any ideas, I'd be very grateful!

paintman · 06 September 2021, 22:38

Next time it does it take the plug out and check to see if it's wet with fuel.

TmMorris · 06 September 2021, 23:03

There were some posts a week or so ago discussing that 4 strokes needed to be set down a particular way. Having only ever used 2 strokes I was oblivious to this but I'm sure someone will know the details.

diver 1 · 07 September 2021, 07:42

Hi - I've got the same Tohatsu 6hp and got it nearly new after the original owner could never get it started and got fed up with it. I found the way to start is as follows:

1) open fuel vent
2) make sure fuel tap on port side of engine cowl is set to the correct tank (they can run off internal tank or seperate tank
3) pull out choke lever
4) twist throttle through full range 4 times
5) set throttle to start position or slightly more than start on the revs
6) pull starter chord.

Mine starts first or second pull each time if this procedure is followed.

Something quirky about needing to twist the throttle on these things

There is a tiny fuel filter bowl behind the fuel valve too that either blocks with debris or leaks. The fuel valve tends to want to leak everywhere too. Not a great design for a brand new engine but I'm getting used to it now

Mattster · 07 September 2021, 08:20

Thanks all, some things to try.

Tim, I do store on the "preferred" side, but the manual states that it is OK to store on either side, so not sure this is the issue - although I have noticed a bit of petrol leakage when placed into the boot of the car.

Diver, thanks for the detailed procedure - I will give that a go. The funny thing is that I have never actually had any difficulties in starting the engine at the beginning of the day, or whilst on the water during the day. The issue seems to be somehow related to transporting the engine soon after use, and resolves over time (a couple of hours) once it has been left upright at home. This would suggest perhaps (?) a flooding issue, so I'll try the spark plug thing next time and see how it looks.

At the moment, not starting at the end of the day is just a bit of an annoyance, but obviously could be much worse if it starts happening during the day..

willk · 07 September 2021, 08:34

As a side bar to the above (excellent) advice:

Shut off the fuel valve after landing, followed by the vent. When cleaning at home, open the vent first and then the fuel valve. It certainly does sound like flooding during transport.

Poly · 07 September 2021, 08:39

Quote:

Originally Posted by Mattster

...although I have noticed a bit of petrol leakage when placed into the boot of the car.

...and resolves over time (a couple of hours) once it has been left upright at home. This would suggest perhaps (?) a flooding issue, so I'll try the spark plug thing next time and see how it looks.

Quote:

Originally Posted by diver 1

There is a tiny fuel filter bowl behind the fuel valve too that either blocks with debris or leaks. The fuel valve tends to want to leak everywhere too. Not a great design for a brand new engine but I'm getting used to it now

A bit of idle speculation from someone who's not had to routinely put engines lying in the boot of a car for nearly 20 years - you shouldn't have "fuel leaking" - so it sounds like its getting out of the carb and could be causing the flooding. Perhaps its time for the old premix 2 stroke approach of disconnecting fuel to run the carb dry at end of the day.

pumpkinking · 07 September 2021, 16:58

Quote:

Originally Posted by Poly

disconnecting fuel to run the carb dry at end of the day.

I do this with my Suzuki DF6A, at the end of the final voyage of the day, I disconnect the external fuel tank, switch the fuel selector to the cutoff / external tank position, and let the motor run itself dry.

I also pretty much follow Diver 1’s starting technique, only addition being that I slowly pull the starter cord until I meet resistance, let the rope retract, then pull to start. This sets the piston in the optimal position for starting, as mentioned by others.

Good luck!

TonyM · 13 September 2021, 19:55

At the end of your trip, run the carb dry while you are finishing up. Make sure of course the tank vent etc is shut then transport it as the OEM recommends. See if it still does it when you get home having run the carb dry before transporting.

Mattster · 13 September 2021, 20:48

Thanks guys, I think that's what I'll do next time. I did mean to do it after yesterday's run out, but forgot - so I just left the engine on the stand for a couple of hours after I got back, and it started first pull.. it does seem likely that it is just flooding when put on its side, and it hasn't been any trouble starting at start of, or during, the day so not really a major issue I guess.

TmMorris · 13 September 2021, 22:13

Not worth checking the engine oil hasn't been contaminated?

TonyM · 13 September 2021, 22:21

Quote:

Originally Posted by TmMorris

Not worth checking the engine oil hasn't been contaminated?

Very good point and at 15h old time to change it anyway really.

TmMorris · 13 September 2021, 22:52

Quote:

Originally Posted by TonyM

Very good point and at 15h old time to change it anyway really.

That was my thought. A few flooding events and a bit of fuel will have gone down passed the rings. I imagine the oil reservoir is quite small on an outboard and I seem to have a figure of 2 or 3% contamination being enough to impact the lubricating effect. Probably doesn't really matter given normal leisure use.

TonyM · 13 September 2021, 23:05

Given the quantities it’s unlikely to affect the lubrication properties but absolutely best practice. Most likely is that fuel is dribbling through the carb, if the inlet valve is open it’s then picking up some oil and passing into the top end of the piston and contaminating the plug which is preventing the start until it has evaporated but what can also happen is the reverse with the sump oil tracking into the carb and contaminating the fuel going into the chamber. Either way an oil change would be a good call. Nice name by the way….Best regards…Tony Morris 👍