Engine won't start - 15HP Mariner Marathon 2 stroke

[ben324]

I am new to boat engines. This is my first one, and it won't start.

I have tried everything to get this engine started. The spark plugs are sparking, the carb seems in good condition. I have just brought a new fuel tank and fuel line. The engine has fresh fuel. And it still doesn't sound like anything is firing in the engine.

Here is a video

https://www.youtube.com/watch?v=LYUejwp3Q74

I am clearly doing something wrong, but I don't know what.

Any help will be greatly appreciated.

[Allye]

First thing first, take a plug out and rest it against the block and turn the engine over to see if you have a spark (don’t touch the plug whilst turning over)

Sounds ignition related if it’s not spluttering are all. Have you got the kill switch in? Apologies if insulting intelligence.

[ben324]

The spark plugs are sparking. Carb seems clean from the front. I will double check everything tonight. I am really lost to what could be wrong

[paintman]

Have you ever seen the engine running?
Are the plugs wet with fuel?

[spartacus]

First off, get the cowl back on the engine. If that Mariner springs into life you'll know about it with your fingers and that flywheel. Let's just say you won't be tinkling on the ivories any time soon!

2-strokes, then fuel, air, and spark.

Allye's point regards the safety kill-switch is a good call. Check the wiring behind the kill-switch.

Assuming it's in, it does sound reluctant to start. Mind you being able to pull the recoil starter with a better stance would help, so see if you can weight that bin a bit more so you can do that.

Back with the fuel tank, new fuel (and 2-stroke oil I hope). Check the fuel-end connection where it goes to the engine. Check it's seated properly and it's actually pumping fuel through. You can press a screwdriver against the fuel-connection ball and it will squirt fuel. With the primer bulb it should go hard. Also ensure the fuel tank is vented. There's also a fuel filter on the engine - it should be full.

Do you know the carbs are clean and are getting fuel? On the carbs, there's a fuel bowl under each carb. There will be a brass hex nut. Ease that off and see what kind of fuel comes out. If there's any sediment, then stop and clean them.

Take the spark plugs out. If they are black (carbon build-up), oiled, then replace. If they are just wet with fuel, then dry them off. Before re-inserting them, leave the sparks out and pull the starter rope a few times to ensure there's no friction when you turn it over.

Also check the HT leads condition.

Pull the choke out, and adjust the throttle marking to start, now try pulling it over again.

[jeffstevens763@g]

take a plug out put a small amount of fuel in the cylinder plug back in put the cowl on get a better stance as said and pull harder your not getting the engine turning over fast enough IMO

[Max...]

Presuming the engine was running when you looked at it pre-purchase?

it does not sound quite right even on pulling over but take up the slack on the starter rope gently before pulling.

[A1an]

looks tight

[ben324]

An update: I managed to get the engine working for 5 seconds. Until now I had never seen the engine working. I had been trying to get it to work for ages and all of a sudden it worked, but since this I have now been able to set it to start again.

It seems that it needs a lot of fuel pressure. Something is blocking the fuel from flowing.

[Allye]

Let us look into our crystal ball and find out the problem for you. If you lack the know how or confidence to work on it or strip the carb send it to a marine engineer.

[Nasher]

Ben

I've sent you a PM with my phone number.

These old 2-strokes can be a pain to start from cold, and if you are not used to dealing with them it could be something simple.

Give me a call and we can go through the basics.

Nasher.

[ben324]

A big thank you to Nasher for his help over the phone.

The engine now works.

https://www.youtube.com/watch?v=rg4aTokCOlo

I didn't realize how temperamental 2 strokes are. The engine had many small problems. There was a bit of dirt in the middle of the carb, the throttle was set wrong, there was liquid fuel in both carb and combustion chamber.

Turns out that the only way to sort it was to fix all problems at once and not try to start it after sorting each problem. I had been sorting the combustion chamber, then trying to start, then sorting the carb, then trying to start, then going back to the combustion chamber. It seems that I kept flooding different parts until I sorted everything in one go.

It is very hard to tell what is wrong when the engine is showing no signs of starting. Then all of a sudden it started. At least I have learnt how these things work a bit better now.

I am very nervous of taking my boat a long way out to some island, then it not starting up to get back to the mainland.

[Nasher]

I'm really pleased you got it going.

Nasher.

[Allye]

Originally Posted by ben324

I didn't realize how temperamental 2 strokes are..

They really really are not!

Well done get it going. Beat way to learn.

[Fenlander]

>>>I didn't realize how temperamental 2 strokes are..

>>>They really really are not!

Agreed... particularly those Mercury/Mariner in 10hp and 15hp form.

Usually a second pull start after months in storage and often first pull from cold in use. First light pull from hot too. Idle evenly at lowish revs without stalling cold on choke or hot.

Once you get it sorted it should be a good motor.

[ben324]

After the engine appearing to work I took the boat out on the tidal river Medway and found another problem.

The engine felt like a car with a slipping clutch. it revved like crazy and produced very little power.

After half an hour the engine was producing no power at all and we had to row the boat back.

I feel very stupid as I kept reving the engine at full power to try and make it work. I was effectively putting it in full power while in neutral. I am worried that I have damaged the engine.

I have made a video

https://www.youtube.com/watch?v=3YAAecY2kVw

I am hoping the problem is just the propeller and not a major gearbox problem.

Also, what propeller do I need to buy for my engine (15HP Mariner Marathon 2 stroke). I am using it on a 3.6 meter SIB and I want to go as fast as possible.

[Allye]

Unless that prop is properly mangled you’ve got engagement issues. Dog selector in the Box is potentially buggered.

That water out the leg is concerning too.

[Nos4r2]

From the video, I would hazard that your exhaust gasket (powerhead to leg) has blown and the prop hub has either spun or you've broken a shear pin depending on the prop/gearbox type (there's 2 for that motor). You'd hear it if the gears were knackered.

Realistically it now needs to go to a marine engineer to find out if it's worth saving. It could be excessive corrosion caused the gasket to blow out. If this is the case, it's usable as spares only.

It probably needs the powerhead removing to check, which on an old motor like that will have all sorts of pitfalls involving seized bolts possibly snapping which are way beyond beginners level to attempt.

[billows]

If you want to educate yourself about outboards this bloke is good if you can stand the accent

https://www.youtube.com/watch?v=hYPuB9nmS8E

[Fenlander]

Ditto folks comments above.

You really need to find out where that excess water is spouting from... either badly failed gasket or corrosion. Try it in the tank at home and see.

Effectively there is no drive at all in the latter part of your video so it should be easy to check by hand if the prop is spinning on its hub.

I agree there should be more nasty noises if the gearbox had failed internally.

One thing though... could it just be the gear selector isn't putting the gearbox into gear because of a broken linkage of perhaps even it's rattled badly out of adjustment?? Did it work in reverse?

Hate to be negative but... ever given how you like to take a degree of risk... that doesn't look like a motor for nipping out to explore the Thames forts!