Mercury 402 2-stroke outboard (no spark?)

RetroRuss · 29 December 2007, 23:57

I have a recently serviced Merc 402. Started OK last week but will not turn over today. Petrol is getting through... is there any trick to starting these old engines, way to hold your mouth, things to watch out for, be careful of? What should I check?
Thanks very much in advance for any advice offered.
Regards,
Russ

Nos4r2 · 30 December 2007, 00:11

What do you mean by 'won't turn over'? Is it siezed? Can you turn the flywheel by hand?

RetroRuss · 30 December 2007, 16:24

No, it's not seized, just will not "fire". I've charged the battery and still no luck
Regards
Russ

Pete7 · 30 December 2007, 18:05

Obvious point first, is the kill switch in place. Plug leads on the right cylinders and all wires connected up?

Used to have one of these, it loved easy start first thing in the morning.

Pete

Hightower · 30 December 2007, 18:14

Kill cord is the classic one, saw a boat my local slip a couple of years ago. The owner had already driven home to pick up a new battery and was using this one up at a rate of knotts. I suggested they connect the kill cord....Lots of red but happy faces all round when the outboard roared into life.

RetroRuss · 30 December 2007, 21:24

Where is the kill switch, or if different kill cord?
Cheers,
Russ.

Nos4r2 · 30 December 2007, 21:47

402's mostly don't have killcords-they are too old to have them fitted as standard on the old blue controls.

Check for a spark with a plug you know works. If you've got no spark, you need to take it to the guy who serviced it. DON'T try and open the ignition box (I assume it's the type without seperate coils)--AFAIK it's a sealed unit. If it does have seperate coils, again, DON'T mess around with them-the low tension side of the ignition on those engines runs at about 100v and you'll fry a multimeter testing it if it's working. You're pretty much limited to doing resistance checks on the coils and stator when they are disconnected.You'll need a manual for it to get the correct figures to check the coils,
The stator should show infinite resistance to earth (ie a broken circuit) and a low resistance reading between the wires coming out of it.

You don't need to test continuity on the yellow wires from the stator. They are simply for charging the battery-the ignition system is a standalone system which generates it's own power-they aren't part of it.

Also check the mercury tilt switch-you'll get no spark if it's loose and has tilted. Unscrew it and wrap it in tape to prevent contact then check for a spark again-they do go wrong occasionally. It should only be giving continuity across it with the engine tilted.It's on the side of the thick ally plate you'll see when you pull the 'thunderbolt' cover off.

RetroRuss · 31 December 2007, 03:25

Thanks for your help and advice. It's looking more and more like I will need to wait until after the holiday period to take it in for a serviceman to check out (I'm not going to mess with this unless it's a simple job).
It's frustrating because it was running fine a few days ago. The motor was always only used in fresh water (until now). The boat was garaged and cared for, so (for it's age) looks in very good condition.

Recent work includes:
All shift shaft seal and drive shaft seals replaced
New gear oil
Gearcase vacuum tested OK
Spark & compression tests OK (compressions #1-160 #2-155)
Replaced fuel pump diaphram
Replaced battery terminals
Checked water pump
Replaced impellor due to wear
Greased propellor shaft
Checked carburator settins and synchronisation
Water cover gasket replaced
Run de-carbon through engine
Checked engine running to temperature

I have attached more photos, for those who are interested, to see the motor more clearly. I couldn't find the tilt switch. Any further comments are most welcome.
Best wishes for the New Year to you all,
Russ.