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Tohatsu 18hp 2 stroke engine stalls

frankn

New member
"I have a tohatsu 2004-5 18hp

"I have a tohatsu 2004-5 18hp 2 stroke with approx 100hrs use,recently serviced, new plugs.It starts,spits a bit, and runs fine for about 10 mins. then dies as if u were trottling back.Put it into neutral for a moment and away again for a minute or two and it dies again.Been told it could be dirt in carb or faulty coil?? Can anybody help?"
 
"Hi
I have checked fuel lines


"Hi
I have checked fuel lines, put in new clean mix,had a mechanic have a look, but no joy.Should I have carb removed?"
 
"OK, was with a mechanic when

"OK, was with a mechanic when he checked out the fuel system, all seemed good.He then removed the carb., no problem there.Put everything back together, still the same problem. He was checking the compression when water pissed out of the cylinder??? Any ideas???"
 
have your mechanic check the g

have your mechanic check the gasket under the power head thats what was wrong with my 40d if thats not it check the exaust plate but be very careful this bolts may break!!!!!
 
"Thanks Louis, passed ur comme

"Thanks Louis, passed ur comments on to my mechanic.
Tohatsu Guru, would u have anything to add?
Thanks
Frank"
 
"Hello again, I ran engine on

"Hello again, I ran engine on boat other day and noticed a lot of water coming out of exhaust outlet? Is this engine a wet or dry exhaust system?"
 
Wet. You will also find that t

Wet. You will also find that the faster the RPM the less water you will see come out that port as the increased pressure forces it out through the prop.
 
"Had mechanic strip down engin

"Had mechanic strip down engine, block not cracked, turns out to be electrical problem.Said there is some sort of elec. unit that neeeds replacing and they are quiet expensive here in ireland.Does this make any sense to anyone?"
 
"ok, but can u tell me anythin

"ok, but can u tell me anything about this elec. unit on the engine, cost of replacement etc
FN"
 
"Which ignition part...The eng

"Which ignition part...The engine ignition system has to be tested, as outlined in the service manual, to determine which component is at fault."
 
""Which ignition part...Th

""Which ignition part...The engine ignition system has to be tested, as outlined in the service manual, to determine which component is at fault."

There are three different coils on that engine. If one tests bad then that coil would need to be replaced."
 
I also have a problem with a Tohatsu 18hp outboard motor and would appreciate it if you could help with the diagnoses.



The motor will sometimes run well for up to 1 hour and then would cut out on the bottom cylinder and then run up again on two cylinders for approx 30 seconds up to a few minutes and then cut out again on the bottom cylinder and run just on one cylinder for a minute or so and then go again on two cylinders for a short while again. it would continuously do this, once it started doing it. It did this on 3 days and on the 4th day it did it right from the start. It made some popping type noises now and then while it was missing and sputtering.



I have cleaned the Carby,and fitted another one just to be sure and fitted another good HV Coil, cleaned the tank and Mixed fresh fuel, with no difference, so I am now picking it to be the lower oil seal on the crankshaft. I have struck this similar thing on another make of motor, where it would run for a while and then start missing and mucking around. In that case it was the lower crankshaft seal.

The Motor is a Tohatsu M18C, 350A

I have since fitted a new lower crankshaft seal and absolutely no difference. I have checked the exhaust ports which are clean and checked the inlet reed valves which all appear to be OK. There is another motor the same here on Niue Island that has similar symptoms. I have had these 12 - 18 hp Tohatsu's for 25 years and have never struck this problem before.

Anybody out there with some insight into what the problem might be I am all ears. Thanks
 
In the US, we don't have anything of that vintage, but if it is a siamese ignition coil (as are the newer 18 2-strokes), it's doubtful that the coil is an issue, as both plugs fire at the same time. I would test and verify ohm readings on the ignition components, and verify that the carb is perfect. I would also do a compression check. If that cylinder shows low compression, it will be more succeptible to misfiring from minor mixture and ignition problems.
 
Hi, was wondering if you ended up working out what the problem was? I have the same problem at the moment, have changed pretty much as listed above but can't work it out. Any help would be greatly appreciated. Thanks
 
I also have a problem with a Tohatsu 18hp outboard motor and would appreciate it if you could help with the diagnoses.



The motor will sometimes run well for up to 1 hour and then would cut out on the bottom cylinder and then run up again on two cylinders for approx 30 seconds up to a few minutes and then cut out again on the bottom cylinder and run just on one cylinder for a minute or so and then go again on two cylinders for a short while again. it would continuously do this, once it started doing it. It did this on 3 days and on the 4th day it did it right from the start. It made some popping type noises now and then while it was missing and sputtering.



I have cleaned the Carby,and fitted another one just to be sure and fitted another good HV Coil, cleaned the tank and Mixed fresh fuel, with no difference, so I am now picking it to be the lower oil seal on the crankshaft. I have struck this similar thing on another make of motor, where it would run for a while and then start missing and mucking around. In that case it was the lower crankshaft seal.

The Motor is a Tohatsu M18C, 350A

I have since fitted a new lower crankshaft seal and absolutely no difference. I have checked the exhaust ports which are clean and checked the inlet reed valves which all appear to be OK. There is another motor the same here on Niue Island that has similar symptoms. I have had these 12 - 18 hp Tohatsu's for 25 years and have never struck this problem before.

Anybody out there with some insight into what the problem might be I am all ears. Thanks


Any idea on what the problem actually was? Thanks
 
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