Non runner?

[solentranger]

Hi,

I have a small 2 cylinder 7.5hp mercury outboard (approximately yr 2000).
It had been running ok but I very rarely use it. I tried it the other day and it started ok with a fresh bit of juice, a few pulls & plenty of choke.

Whilst fiddling with it she stopped running & failed to restart even after numerous attempts.
I took the plugs out & one was an oily black (wet) and the other was a coked (dry) sooty black.

Any ideas fellas?

Fingers crossed, thanks.

[backdraft]

try striping the carb,maybey the float was stuck down (crap in carb ). give the plugs a real good clean. and try again.

baz

[scotty]

Get yourself some insulated pliers and do a spark test, hold your plugs against a good earth on the powerhead and pull the engine over as you would if you were starting it.

If you dont get a spark do a continuity test between your live feed on your coil and the end of the HT lead

If both plugs spark, let a mercury dealer strip your carb, i wouldnt recomend you do it yourself unless you already have some experience with carbs

[solentranger]

Cheers Fellas!

Update -

I done a spark test & the plug to the top cylinder wasn't sparking.
Next, I swapped the plugs around and the plug that was originally not sparking in the top cylinder did spark in the bottom cylinder ht lead, also the plug that was sparking from the bottom cylinder didn't spark when in the top cylinder ht lead.

Both plugs are ok but there's obviously a problem from the top cylinder ht lead or somewhere before it?

How do you do a continuity test? if the ht lead is ok (no sign of any fault) where would the fault then be?

Scotty - some instructions on your continuity test between the coil & the ht lead would be great mate!

Cheers all

[scotty]

you will either need a purpose continuity tester OR a multimeter set to the ohms setting, either one will do.

If you have a continuity tester, touch one of the probes where the live feed to the coil comes in, then touch the other end inside the HT lead, where the plug goes. if you have cotinuity a light or a buzzer should sound.

If your using a multimeter do the same as with the continuity tester, but if you have continuity the needle should fall to zero, or fairly near it

If you dont get continuity then you coil has broken down(which is probably the case)

I can supply one for you if you need one

[solentranger]

Nice one Scotty - cheers :cheers:

The only wire going to the bad coil is a green / yellow stripe with a ring connection that goes onto a nut & bolt on top of the coil.

I haven't done a continuity test but I'm going to replace that coil anyway.

By the way, could the problem be before the coil ?

[Pete B]

Sounds like this -





I'm doing the same job.
I'm no mechanic but what I done to find out if the problem was definetly at the coil & not before it was move the 'power in' wire (green / yellow stripe on yours) from the bad coil to the good coil and then tested the plug against the powerhead.
If the plug sparks then you know everything upto the bad coil is ok and the problem is the coil.

Scotty - you have a pm mate.

[scotty]

It is possible that the problem could be before the coil, there should be either a switchbox or a CDI unit before the coil(not entirely sure though) which could be faulty.

Your best bet is to test the coil before you replace anything, either a continuity test or the way pete did.

If you test the same way as pete remember to connect your coil wires to the correct coils afterwards or your firing order will be backwards

scotty.