2002 Mariner 4hp 2-Stroke - No Spark

AndrewOR · 06 July 2021, 12:37

Hi all,

I have a mariner 4hp 2-stroke outboard, Serial Number OP158789, Year 2002 4M.

I have a basic understanding of outboard mechanics and their electrics. But I am aware that I am consciously incompetent. That is to say, I know a little - not a lot.

This engine was bought new, and was lightly used on a tender for a few years, before being flushed, and stored in a garage for a few years.

In 2017, it was brought back into commission and it ran perfectly until it was accidently submerged by visiting and overenthusiastic helmsman.

Since then, I have managed to get the engine running, but never consistently or in a manner that sounded healthy and gave me confidence. (cyclinder was flushed, oils changed etc.)

In truth it has ran for sub 10hrs runtime since it was submerged. The problem being intermittent sparking, and also I suspect fuel/carb issues.

I know the economics are not viable, but I am confident that it is rescuable, and ultimately I want to understand what the issues are (call it an educational process).

To tackle the intermittent sparking issue the engine has had:

(1) Carb Stripped and cleaned including jets
(2) Carb gaskets, float, and needle replaced and set
(3) Spark plug replaced and correct gap verified using feeler gauge
(4) Ignition coil replaced
(5) HT lead replaced
(6) Fuel filter replaced
(7) Fuel tank cleaned
(8) Fuel Lines Replaced

However, I now have no spark.

I fear it could be the stator. However i have not been able to remove the flywheel (no flywheel remover tool...and the more creative diy approach has not been successful)

Of course, it could also be the trigger, and/or the cdi box.

All of these items are quite expensive (given the age of the outboard the economics question gets raised)

So I would like to be able to test around these items (especially the cdi box) to confirm before I purchase.

For this, I require a workshop manual to determine the ohms resistance readouts that i should expect to see.

Does anyone have such a manual for the engine listed above? I've struggled to find one, and would very much like to get to the bottom of this.

Thank you for your help.

Regards,
Andrew

spartacus · 06 July 2021, 20:02

I'm not surprised its not sparking now if its been submerged, then laid up for a period of time, but everything you've mentioned in terms of servicing and remedial work is spot on so won't have done it any harm.

One thing to note is the wiring itself. It's not tinned wiring, so oxidisation or corrosion can prove to be a pain to track down. Pull the bullet connectors apart, lightly sand and reconnect. A cheap multimeter is a good way to test continuity and rule out issues. Also check the wiring from the engine kill switch to rule that out.

Also the wiring under the flywheel is definitely worth investigating, especially the stator plate and sender coil. You should be able to rig up a puller on a 4hp with threaded bar and scrap metal if you have that at hand.

Saw this and it made me smile. You're not alone!

https://www.justanswer.com/boat/7m95...k-cleaned.html

AndrewOR · 06 July 2021, 20:33

Hi Spartacus.

Many thanks your reply.

Mmm I thought the wiring was looking a bit dull. ��

I'll have to do some disassembly to check everything, but of those wires that are immediately available, continuity is ok.

This again suggests the problem may be under the flywheel...

I don't have a compression gauge but can confirm that clingfilm over the air intake was sucked in with impressive gusto.

Unfortunately my wiring colours don't match the advisors in your link... however they do match the poster's.

I can confirm the dead man wiring is healthy.

Regards,
Andrew