Tohatsu 3.5 Won't Start

[sandy daugherty]

Unfortunately, the Tohatsu/Nissan/Mercury/? 3.5 4 stroke has an integral tank and no room under the hood for a water separating filter. The good news is that the translucent tank will reveal water in the low points in a good light. Pull the line from the tank and drain the water. Drop the bowl and spray some carb cleaner into the inlet line and blow it through. Eventually the clot will dissolve around the jet. Then from now on shut the engine down by turning the fuel off, and wait for it to stop.

Cupping your hand over the intake while pulling the starting rope will occasionally pull enough vacuum to clear the snot around the jet.

[donradcliffe]

Try a shot of quick-start (ether) down the carb. If it won't fire with that and a clean, dry plug, its an electrical problem.

[Ex-Calif]

Is the engine running yet?

Check spark first - Remove the wire from the plug - Hold it with a pair of insulated handle pliers very close to the metal part of the engine.

Pull the start cord. If you get a spark you can eliminate any kill switches from the problem list.

If you get a spark, pull the spark plug. Look to make sure there is a small gap (a folded over matchbook cover should slide in) between the curved electrode and the center pin. Plug the wire in the spark plug. hold the threaded part of the spark plug against a metal part of the engine (not a painted part). Pull the ripcord. if you see a spark jump the gap, you likely have a fuel problem.

[Morgan 27]

Getting spark??? That'll tell the tale on where to go... My buddy has one he simply refuses to work on and it's still running. Corrosion and all. The kill switch works by grounding out the spark so any wire disconnected to/from will take it out of the loop. Unscrew the plug, hold up to motor and spin 'er over. Spark should be visible in broad daylight!
Mike Sr.

[wlshor]

I had brought a new Nissan 9.5 and at the lauch the motor would not start. After many pulls. I removed the cover and found that the choke was closed. When I pulled the choke the first time. The plactic piece that connected the choke had pulled loose and left the choke closed. I reattached the plactic piece and pull a few times and motor ran fine. My lesson was be careful of not pulling the choke too hard and pulling the plactic piece loose.. Never had a problem since. Motor is two years old now.

[roberttigar]

To eliminate question of a fuel problem, spray ether starting fluid into the carb, wait a few seconds and pull the cord. If the engine fires, its a fuel prob, if it doesnt fire then its probably electrical. Bob

[Talbot]

I dont really do very much to my outboard other than drain the fuel from the carb each time it is uded by letting the motor die by fuel starvation, and giving the cooling water passages a clean every couple of years.

Never had any real problem with either a yam 2hp or a tohatsu 3.5.

[roberttigar]

The most difficult part of solving a mechanical problem is deducing what it is. In the case of an outboatd not startingits either the fuel system or electrical. If ether gets it started then you can eliminate the fuel system as the problem. If it starts and stops, the fuel may have been contamiinated. If the engine doesnt fire at all, then its probably electrical. Bob

[RBEmerson]

Originally Posted by midnightstar

hey there!
my outboard wont start.just replaced the spark plug and cleaned the carborator.
electrical problem?

What does "cleaned the [carburetor]" mean? That is, did you disassemble or...? If you tinkered with the carb and didn't put it back together correctly, that'd kill the motor in a heartbeat.

Spark check: take the plug out, hold the threaded bit against the cylinder head, and pull the starter chord. A spark should show up across the plug's electrodes. BTW, make sure whatever you use to hold the plug in place is well insulated or you may find out, the hard way, there's a good spark.

[rlbrown]

My Merc 3.5 did the same thing. Tohatsu makes them for Merc. It was the ignition module. I went through 2 of these engines. Trust me. Get it tested .

[JHJH]

I have an older 3.5 HP Tohatsu outboard that I bought used with a sailboat. It does not have a fuel pump. Gravity fed fuel from the tank. It was hard to start and would idle slow and then stop. After cleaning the carburetor making sure the jets were clean it still would not run. Then I pulled the 2 vent tubes off the side of the carburetor and they were pugged up and you could not blow air through them. Started the motor with out the tubes attached and it ran perfect! My guess is that spiders or bees stopped them up. I cut a few inches off the vent tubes and was able to blow debris out. So check out the vent tubes to make sure you can blow through them before anything else!!! That is the easiest thing to try first.
The piolet jet is the low idle jet on the carb. It has the smallest holes for fuel to pass through and are the most likely to stop up. The piolet jet is removed externally on the side so you do not have to remove the carb bowl to clean. The best thing to clean jets with are micro drill bits that are used to clean burner tips with. A set cost 10 or 20 bucks. Stranded wire pieces may work as well.

There is a air mixture screw on my carburetor. Not all Carburetors for this motor will have one. If yours does you typically screw the jet all the way in and then back it out 1.5 turns as a starting point on most carbs.

Those are the basics. Check the vent tubes and see if you can blow through them. They pull right off. Happy sailing!

[rsn48]

For smaller engines including lawn mowers and spray washers, use Chevron 94 gasoline, it doesn't have ethanol added to the fuel. This helps to reduce future problems.