Trouble with starting engine.

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hugotthomas

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Hi everyone, I'm new here and I apologise in advance if this is the wrong thread to post in but i'm having a few issues with trying to start my Tohatsu 3.5 hp (m3.5b2) and was wondering if any of you guys could help.

It hasn't been used for a couple of years now and I found it in the garage and really want to get it going again. After being sat in my shed it's no wonder it didn't start - I have now cleaned the carburettor, checked the impeller, bought a new spark plug and still the thing won't fire, I've taken the spark plug out and earthed it against the engine but still no luck with getting a spark.

I've seen similar threads about disconnecting the ignition kill switch to test it but was not quite sure how to do that? Do I just disconnect the 2 wires leading from the stop switch?

I'm not sure what to do next, if anyone can give me any pointers i would be very grateful.

Thanks a lot

Hugo
 
One of the wires (brown) from the kill switch should go to the CD unit, it may be easier to disconnect that one rather from the switch itself.

PS... you are plugging in the kill switch lanyard? :o
 
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Thanks for the quick response Kev, just tried that and still not getting no joy/no spark.

After having a few attempts at getting it going, if i take the spark plug, it sticks of petrol there which suggests the fuel system is ok and so it's more of a electrical issue i think?!

How would i go about testing each electrical part? (i've had a look online for replacements and i don't fancy having to get all news ones!!) If i can find out which bit of the ignition system has given up on me could i just replace that and then would we be good to go?
 
small outboards can be tricky devils. The kill switch shorts out part of the ignition circuit. If you follow the wires back from the switch there is usually a cluster of bullet connectors. Disconnect the lead from the kill switch. The other thing to try is take of the ignition coil and clean all the contacts and the bare metal face where it bolts onto the motor. If none of that works it could be the sense coil or the ignition module itself which will probably need professional help on. You can often find parts on ebay so if cheap might be worth a bit of swapping and changing.
 
I agree the first thing to do is to get a spark.

Start as suggested by checking that the stop switch is not shorting out. ( and new plug, but youve done that)

Good idea to use some sort of spark tester rather than holding the plug against the engine ... even an improvised one.


Ignition system consists of an exciter coil (#2) Inspect condition and check continuity.

CD unit (#9). requires special equipment to test, see below

and the ignition (HT) coil (#6) Check continuity of primary and secondary windings.

Check all wiring for shorts and good connections.

Some info on testing ignition systems in the CDI Electronics troubleshooting guide at http://www.cdielectronics.com/support/ but you need a DVA adapter for a multimeter ( easy to make if you are so inclined)

When you have good spark that will jump best part of a cm, Move on to the fuel/carb if still no go


NS2A2-3A2-3B2-1998-fig-3.png
 
Hi again everyone,

Thank you very much for everything, all very helpful suggestions.

Kashurst: I've tried disconnecting the stop switch and tried with a spark plug tester instead of just grounding it against the engine but still no luck. Also cleaned all the contacts and where the ignition coil screws onto the engine - still no joys.

VicS: really helpful stuff, thank you.

I'm currently trying to remove the flywheel to get to the exciter coil so i can clean the contacts and give it a test.

Does anyone have any recommendations how to clean the contacts in the rubber bullets connectors? The other side and the rings are obviously easy to clean up just wondering if one of the bullets is dirty.

I shall keep everyone updated with he progress. Thanks again
 
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