tohatsu 30 missfire

[shetlandseagem]

I bought a new Tohatsu 30 last year. The engine ran well, over winter it was serviced and stored by the dealer. First run this year the oil light flashed on and the engine missfired at the same time. Tried it on the mooring and the same again but I could hear the "snick" of a high tension sark jumping, this coincided with the oil light flashing on and the engine missfire. I have contacted the dealer but would really want some background info, is this a common fault?

 

[pvanv]

Re: tohatsu 30 missfire

No, it's not common. Maybe a plug wire is loose... One could open the cowl and look... After all, it's prudent for the operator to check the motor before operating it... things like checking oil, etc... But then you should be under warranty, and the dealer likely should have checked it over before returning it to you. Did they also do a 10-hour or annual service while storing the motor?

 

[shetlandseagem]

Re: tohatsu 30 missfire

Service and storage done by dealer. Engine refitted by dealer. I checked oil level before starting and when the problem arose I removed the cover to check. Definately not a loose plug cap, the HT spark sounds to be somewhere high and just aft of the centre of the engine. As it was bright daylight I was unable to see the exact position. The dealer is looking into the problem but sometimes it is good to know a bit of background to these things...

 

[pvanv]

Re: tohatsu 30 missfire

That's a weird one. That motor has 3 individual coils, all far aft and on the port side. That's the only place one would likely find HT voltage that could cause an arc. However... that sound might not actually be an arc. I would definitely have the dealer check it over.

 

[shetlandseagem]

Re: tohatsu 30 missfire

Thanks, definately an arc though. Just remembered that when I went to the boat after it had been serviced the ignition had been left on and the battery was completely flat. Is that significant? As for arc location is ther anything under the flywheel? Dealer inverstigating but i am very curious as to the fault. Otherwise a great engine!

 

[pvanv]

Re: tohatsu 30 missfire

I suppose something might have gotten hot if left "on" without running for days. The only thing under the flywheel is the alternator and the pulser coils -- all relatively low voltages. I would definitely like to hear about the outcome on this one. I love the 30B motors... start and run like a car... very smooth and no carb "stumble", being 3-cyl EFI motors.

 

[shetlandseagem]

Re: tohatsu 30 missfire

Just heard back from the dealer who says there was a loose earth lead and all is now well though I have not yet been down to the boat to try it myself. If the earth lead was jumping contacxt I can imagine it causing this sort of problem, one query though is can it cause a problem with the alternator? Hopefully all is now cured and I can get on with using the boat! Thanks to all for their inputs.

 

[TOHATSU GURU]

Re: tohatsu 30 missfire

A loose ground can cause a variety of problems while it is loose. It would be rare, though not unheard of, for it to actually damage another ignition part.

 

[shetlandseagem]

Re: tohatsu 30 missfire

It's not over yet.....

Went to the boat, did engine checks and started it up. Started perfectly and ticked over smoothly, allowed the engine to warm up then put some revs on while not in gear, nothing excessive. Oil light came on and then went off when I lowered the revs. Repeated the sequence and each time I increased the revs the oil light came on.

Now begining to loose confedence in engine and dealer.....

 

[pvanv]

Re: tohatsu 30 missfire

What is your oil level on the dipstick?

 

[shetlandseagem]

Re: tohatsu 30 missfire

engine serviced and oil changed by dealer who also came out to fix the earth lead. Will check but if low then my reservations concerning the dealers ability will be confirmed.....will let you know.

 

[TOHATSU GURU]

Re: tohatsu 30 missfire

It could still be a ground issue.

 

[pvanv]

Re: tohatsu 30 missfire

Sure could be. The tech can verify the oil pressure by using a mechanical gauge. The LED operates when the sender grounds out, so it could be showing a false signal.

 

[shetlandseagem]

Re: tohatsu 30 missfire

Thanks for all the abaove, I went back to the boat today to check the oil level (which I was sure I checked last time but being an automatic sequence I thought I should check again!).

Oil clean and up to the correct level. The earthing issue sounds plausible, certainly no missfire this time but as the revs increase then I assume so does the output from the alternator, maybe a correlation.

All very irritating, nice to hear the engine running again though if only for a short period!

Thanks to all once more.

 

[TOHATSU GURU]

Re: tohatsu 30 missfire

You can also try pulling out the oil sender and cleaning it. You may have some debris in it.

 

[shetlandseagem]

Re: tohatsu 30 missfire

Just to let everyone know who helped. The loose earth was the problem and the engine now runs perfectly as before. There are no lasting problems with either the ignition or charging caused by running the engine with intermittent earth connection. Thanks to all.

 

[TOHATSU GURU]

Re: tohatsu 30 missfire

Yep, I'm a freaking genius in this thread....Now if only those inflatable guru wannabes would realize that